User's Guide - Special Olympicsmedia.specialolympics.org/resources/health/...SAHARA Clinical Bone Sonometer WARRANTY, SOFTWARE LICENSE, & LIMITATION OF LIABILITY ( Sahara ) The following

User's Guide

Document No. 080-0631 Revision D

SAHARA Clinical Bone Sonometer

January, 1998

The information contained in this Manual is confidential and proprietary to Hologic,Inc. This information is provided only to authorized representatives of Hologic'scustomers solely for the purpose of facilitating the use of Hologic's products. Noinformation contained herein may be disclosed to any unauthorized person for anypurpose whatsoever without the prior written consent of Hologic, Inc.

©Copyright 1997 and 1998 by Hologic, Inc. All rights reserved.

The Hologic logo and the Sahara logo are registered trademarks of Hologic, Inc.

Printed in the U.S.A.

All trademarks, registered trademarks, and product names used within this documentare the property of their respective owners.

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WARRANTY, SOFTWARE LICENSE,

& LIMITATION OF LIABILITY

( Sahara )

The following terms are an essential part of your agreement with Hologic.By using any Hologic equipment covered in this manual, you agree to bebound by these terms. If you do not agree to these terms, you must contactyour Hologic representative within five days of receipt and we will arrange toenter into a written agreement or for your return of the equipment.

WARRANTY. All Hologic products are warranted to the original purchaser orlessee (“Buyer”) to perform substantially in accord with their published functionalspecifications and to be free from defects in material and workmanship under normaluse as prescribed in Hologic’s Clinical User’s Guide as of the date of Hologic’sshipment (“Delivery”). This warranty shall extend for one year from the date ofDelivery. Hologic does not warrant that use of products will be uninterrupted orerror-free. This warranty shall not apply to any product that is: (a) repaired or alteredother than by Hologic or its authorized service personnel; (b) subjected to physical orelectrical abuse, stress, neglect or misuse; or (c) supplied on a pre-release or “as-is”basis.

If any product fails to meet this warranty, Buyer’s exclusive remedy andHologic’s entire responsibility shall be for Hologic (at its discretion) to repair orreplace the non-conforming product or part thereof, or to return the price paidtherefor. Any item so replaced or repaired shall be subject to this warranty for theremaining warranty period or for thirty (30) days, whichever period is longer. Buyermust report any product failure during the warranty period and return the affectedproduct or item in accord with Hologic’s instructions.

EXCEPT AS MAY BE EXPRESSLY STATED IN A WRITTEN AGREEMENTSIGNED BY HOLOGIC, BUYER AGREES THAT THEIR AGREEMENT SHALL BEGOVERNED BY MASSACHUSETTS LAW, AND THIS WARRANTY IS IN LIEU OFAND EXCLUDES ALL OTHER WARRANTIES AND CONDITIONS, EXPRESS ORIMPLIED, INCLUDING BUT NOT LIMITED TO ANY IMPLIED WARRANTIES OFMERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.


SOFTWARE LICENSE. All Software is supplied under this license only.Hologic retains all title to and all copyrights to Software and any copies thereof.Buyer is granted a non-exclusive royalty-free license to use Software solely on theequipment on which it is installed at time of Delivery (or on the equipment for which itis intended to be installed, if it is not yet installed when Delivered) for as long asBuyer shall own such equipment. Software may be used for performingmeasurements on this equipment in the normal course of Buyer’s business, but forno other purpose or business. No license is provided to use Software for multi-sitequality control or data review purposes. Buyer must maintain all copyright,proprietary and other notices on Software, and must not decompile, disassemble orreverse engineer the Software, and must not make it available to any party exceptthose using the Software as part of their duties.

If the Buyer transfers Software or equipment on which Software is installed to athird party, the Buyer may assign these rights to use Software on the sameequipment to this third party provided that the third party first agrees in writing to bebound by these terms, and to permit Hologic to enforce them against the third party.The Buyer has no other right to sell, assign, transfer, copy or sublicense Software.Any failure by the Buyer to comply with the terms of this license will cause thislicense to terminate automatically. The Buyer may terminate this license byreturning the Software and all copies thereof to Hologic.

LIMITATION OF LIABILITY: IN NO EVENT SHALL HOLOGIC BE LIABLEFOR ANY SPECIAL, INCIDENTAL OR CONSEQUENTIAL LOSSES, DAMAGES,OR EXPENSES UNDER ANY THEORY INCLUDING BUT NOT LIMITED TONEGLIGENCE EVEN IF INFORMED OF THE POSSIBILITY THEREOF (ANDINCLUDING BUT NOT LIMITED TO LOSS OF PROFITS, DATA, OR USE)ARISING OUT OF ANY USE OF THE EQUIPMENT OR BUYER’S ACQUISITIONOF ANY HOLOGIC PRODUCT. UNDER NO CIRCUMSTANCE SHALL HOLOGICBE LIABLE FOR ANY AMOUNT GREATER THAN THE PRICE HOLOGIC HASRECEIVED.

Hologic retains the right to void all warranties, obligations and licenses ifpayment for the subject equipment or Software is not received in accord with theapplicable terms of sale or lease.

Clinical User's Guide v

Table of Contents

1 Introduction and Background .........................................................................................1-1

Essential Prescribing Information....................................................................................1-1Quantitative Ultrasound (QUS) as a Tool for the Assessment of Bone Status ................1-8Sahara Clinical System Overview....................................................................................1-9Ultrasound Measurements Using Sahara .......................................................................1-10Speed Of Sound (SOS)..................................................................................................1-11Broadband Ultrasound Attenuation (BUA) ...................................................................1-12Estimated Heel BMD and the Quantitative Ultrasound Index (QUI) ............................1-13Relationship between Sahara Results and Heel BMD Results obtained by X-RayDensitometry .................................................................................................................1-14Relationship between Sahara Results and Risk of Fracture ...........................................1-15System Components ......................................................................................................1-17

Quality Control (QC) Phantom...............................................................................1-18Ultrasound Coupling gel.........................................................................................1-18Controls and Indicators ..........................................................................................1-19

Specifications ................................................................................................................1-21

2 Initial Set Up......................................................................................................................2-1

Examination Room Environment.....................................................................................2-1Unpacking the System .....................................................................................................2-1Setup and Test .................................................................................................................2-3

Power On the System ...............................................................................................2-3Printer Operation ......................................................................................................2-6

Set Time ..........................................................................................................................2-9Set Date .........................................................................................................................2-11Set Language .................................................................................................................2-13

3 Quality Control..................................................................................................................3-1

Quality Control Procedure...............................................................................................3-2Recording/Plotting QC Results......................................................................................3-11Interpretation of QC Results..........................................................................................3-12

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vi SAHARA Clinical Bone Sonometer

4 Patient Measurement ........................................................................................................4-1

Note about Ultrasound Coupling Gels ............................................................................ 4-1Sahara Patient Measurement Procedure .......................................................................... 4-3

Prepare Transducer Pads.......................................................................................... 4-3Position Patient ........................................................................................................ 4-7Measure Patient...................................................................................................... 4-14

Internal (Strip) Printer Report ....................................................................................... 4-17Patient Report Form...................................................................................................... 4-18Precision of Sahara Results ........................................................................................... 4-18

Considerations for Patient Monitoring................................................................... 4-19

5 Comparison of Patient Results to Reference Values......................................................5-1

Types of Reference Database Comparisons .................................................................... 5-1Reference Database Comparisons Available with Sahara ............................................... 5-2Reports ............................................................................................................................ 5-2

Internal (Strip) Printer Report .................................................................................. 5-2Patient Report Form........................................................................................................ 5-4

Estimating the Z-score and Plotting Patient Results vs. Age DependentReference Values: .................................................................................................... 5-4

Sahara Caucasian Female Reference Database ............................................................... 5-6Study Overview........................................................................................................ 5-6Reference Data Ranges for the Sahara Clinical Bone Sonometer ............................ 5-7

Modify Young Adult Estimated BMD Reference Values (optional) .............................. 5-9Development and Use of Reference Data Ranges for Specific PatientPopulations ............................................................................................................ 5-12

6 System Care and Maintenance.........................................................................................6-1

Ordering Supplies ........................................................................................................... 6-1Cleaning and Re-Use....................................................................................................... 6-1

How Supplied .......................................................................................................... 6-1Infection Control...................................................................................................... 6-2Cleaning Frequency ................................................................................................. 6-3How to Clean/Disinfect the Sahara Unit .................................................................. 6-3

Cleaning............................................................................................................ 6-3Disinfecting....................................................................................................... 6-3Additional Measures ......................................................................................... 6-3Alternate Practices ............................................................................................ 6-3

Care and Maintenance of Transducer Pads ..................................................................... 6-4

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Clinical User's Guide vii

Care of Transducer Pads..................................................................................................6-4Transducer Pad Discoloration .........................................................................................6-4Removal/Replacement of Transducer Pads .....................................................................6-5Calibrate System..............................................................................................................6-9System Calibration ..........................................................................................................6-9Calibration Failure.........................................................................................................6-17Printer Operation ...........................................................................................................6-18Display Serial Number ..................................................................................................6-21What to do in Case of Trouble ......................................................................................6-22

Acquiring Results After a Paper Jam/Clearing a Printer Paper Jam.......................6-22Printer Operates but Does Not Print.......................................................................6-23Power Problem .......................................................................................................6-23System Malfunction and Error Log ........................................................................6-23Printing the Exception Report ................................................................................6-24

Quality Control Problem ...............................................................................................6-25Patient Measurement Problems .....................................................................................6-26

Asterisk after Estimated BMD result (Est. BMD = 0.500* g/cm2).........................6-26Invalid Measurement, Repeat ........................................................................................6-26Measurement Out-of-Range...........................................................................................6-27

FiguresFigure 1-1 Sahara Clinical System ................................................................................1-10Figure 1-2 Sahara Measurement Geometry ...................................................................1-11Figure 1-3 SOS Measurement........................................................................................1-12Figure 1-4 BUA Measurement ......................................................................................1-13Figure 1-5 System Components.....................................................................................1-18Figure 1-6 Power Status Light .......................................................................................1-19Figure 1-7 Control Panel ...............................................................................................1-19Figure 2-1 Unpacking the System....................................................................................2-2Figure 2-2 Power Supply Connections ............................................................................2-3Figure 2-3 Power Status Light .........................................................................................2-4Figure 2-4 Removing Printer Cover ................................................................................2-6Figure 2-5 Threading Printer Paper .................................................................................2-6Figure 2-6 Feed Printer Paper..........................................................................................2-7Figure 2-7 Insert Paper Roll ............................................................................................2-7Figure 2-8 Printer Cover Replaced ..................................................................................2-8Figure 2-9 Press Program, 9, ENTER .............................................................................2-9Figure 2-10 Press PROGRAM, 8, ENTER ...................................................................2-11Figure 3-1 Press ON ........................................................................................................3-2Figure 3-2 Transducer Pads Touch..................................................................................3-3

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viii SAHARA Clinical Bone Sonometer

Figure 3-3 Transducer Pads Ready for Gel ..................................................................... 3-3Figure 3-4 Press PROGRAM, 1, ENTER ....................................................................... 3-4Figure 3-5 Gel Measurement........................................................................................... 3-5Figure 3-6 Spread Gel ..................................................................................................... 3-5Figure 3-7 Proper Amount of Gel on Transducer Pad .................................................... 3-6Figure 3-8 Press OPEN/PREP ........................................................................................ 3-6Figure 3-9 QC Phantom Position .................................................................................... 3-7Figure 3-10 Press MEASURE......................................................................................... 3-8Figure 3-11 Press OPEN/PREP ...................................................................................... 3-8Figure 3-12 Press PRINT.............................................................................................. 3-10Figure 3-13 QC Log...................................................................................................... 3-11Figure 4-1 Comparison of Ultrasonic Coupling Gels...................................................... 4-2Figure 4-2 Press ON........................................................................................................ 4-3Figure 4-3 Transducer Pads Touch ................................................................................. 4-3Figure 4-4 Transducer Pads Ready for Gel ..................................................................... 4-4Figure 4-5 Gel Measurement........................................................................................... 4-5Figure 4-6 Apply Gel ...................................................................................................... 4-5Figure 4-7 Gel Application ............................................................................................. 4-6Figure 4-8 Press OPEN/PREP ........................................................................................ 4-7Figure 4-9 Patient Position.............................................................................................. 4-7Figure 4-10 Patient Leg Position..................................................................................... 4-8Figure 4-11 Patient Foot Position ................................................................................... 4-9Figure 4-12 Heel Position ............................................................................................... 4-9Figure 4-13 Positioning Aid Slightly Loose.................................................................. 4-10Figure 4-14 Correct Leg Angle (front to back) ............................................................. 4-10Figure 4-15 Incorrect Leg Angle (system too close) ..................................................... 4-11Figure 4-16 Incorrect Leg Angle (system too far)......................................................... 4-11Figure 4-17 Correct Leg Position (side to side) ............................................................ 4-12Figure 4-18 Incorrect Leg Position (side to side).......................................................... 4-12Figure 4-19 Incorrect Position of Toes ......................................................................... 4-13Figure 4-20 Positioning Aid Strap ................................................................................ 4-13Figure 4-21 Press MEASURE....................................................................................... 4-14Figure 4-22 Removing Positioning Aid........................................................................ 4-15Figure 4-23 Press OPEN/PREP .................................................................................... 4-15Figure 4-24 Cleaning the Pads ...................................................................................... 4-16Figure 4-25 Press PRINT.............................................................................................. 4-17Figure 5-1 Press PRINT.................................................................................................. 5-3Figure 5-2 Patient Report Form ...................................................................................... 5-5Figure 5-3 Press PROGRAM, 7, ENTER ..................................................................... 5-10Figure 6-1 Remove Transducer Pad Housing ................................................................. 6-5Figure 6-2 Cleaning Transducer Face ............................................................................. 6-6Figure 6-3 Right Transducer Pad Alignment .................................................................. 6-7Figure 6-4 Left Transducer Pad Alignment..................................................................... 6-7Figure 6-5 Pad Gel Application ...................................................................................... 6-8

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Clinical User's Guide ix

Figure 6-6 Pad Guide Marks ...........................................................................................6-8Figure 6-7 Pads Installed Correctly .................................................................................6-9Figure 6-8 Press ON ......................................................................................................6-10Figure 6-9 Transducer Pads Touch................................................................................6-10Figure 6-10 Transducer Pads Ready for Gel .................................................................6-11Figure 6-11 Press PROGRAM, 2, ENTER ...................................................................6-11Figure 6-12 Measure Gel...............................................................................................6-13Figure 6-13 Apply Gel...................................................................................................6-14Figure 6-14 Gel Application..........................................................................................6-14Figure 6-15 Press OPEN/PREP.....................................................................................6-15Figure 6-16 QC Phantom in Position.............................................................................6-15Figure 6-17 Press MEASURE.......................................................................................6-16Figure 6-18 Press OPEN/PREP.....................................................................................6-16Figure 6-19 Removing Printer Cover ............................................................................6-18Figure 6-20 Threading Printer Paper .............................................................................6-18Figure 6-21 Feed Printer Paper......................................................................................6-19Figure 6-22 Insert Paper Roll ........................................................................................6-19Figure 6-23 Printer Cover Replaced ..............................................................................6-20Figure 6-24 Press PROGRAM, 6, ENTER ...................................................................6-21

TablesTable 1-1 Control Panel ................................................................................................1-20Table 1-2 Sahara Specifications ....................................................................................1-21

Table of Contents

x SAHARA Clinical Bone Sonometer

Introduction 1

Advanced Clinical User's Guide 1-1

1 Introduction and Background

This chapter provides overview information about the Sahara Clinical Bone Sonometerwith the Advanced Clinical Software Option (the Sahara “Advanced Clinical BoneSonometer”). It includes a discussion of ultrasound measurement, safety precautions,system components and product specifications.

Essential Prescribing Information

Caution: Federal (U.S.A) Law restricts this device to saleby or on the order of a physician (or properly licensed practitioner).

1. Device Description:

The Sahara Clinical Bone Sonometer consists of the measurement unit, its powercord/power supply, a foot positioning aide, and accessories. The Advanced ClinicalSoftware Option consists of software for an external personal computer, acommunications cable, and an Advanced Clinical User’s Guide. See How Supplied,below, for a complete list of accessories.

Ultrasound measurements are performed on the Sahara system with the patient seated andtheir foot positioned and secured in the Sahara system using a positioning aide. After thepatient’s foot is secured, a pair of soft elastomer pads are brought into contact withopposite sides of the patient’s heel by means of a motorized caliper mechanism. Each ofthe elastomer pads are acoustically coupled to the heel and to a sound transducer usingSahara Ultrasound Coupling Gel. Inaudible high frequency sound waves, produced byone of the sound transducers, are transmitted through the heel and received by theopposite transducer. Quantitative parameters describing the speed and attenuation of thesound waves in the heel are measured.

1

1 Introduction

1-2 SAHARA Clinical Bone Sonometer

The Sahara Clinical Bone Sonometer estimates calcaneal (heel) Bone Mineral Density(BMD, in g/cm2) from the measured ultrasound parameters. Patient examination time isshort, with a measurement time (excluding patient positioning) of less than ten seconds.

2. Intended Use/Indications:

The intended use of the Sahara Clinical Bone Sonometer is to perform a quantitativeultrasound measurement of the calcaneus (heel bone), the results of which can be used inconjunction with other clinical risk factors as an aid to the physician in the diagnosis ofosteoporosis and medical conditions leading to reduced bone density, and ultimately inthe determination of fracture risk.

Sahara measures the speed of sound (SOS, in m/s) and broadband ultrasonic attenuation(BUA, in dB/MHz) of an ultrasound beam passed through the calcaneus, and combinesthese results linearly to obtain the Quantitative Ultrasound Index (QUI). The output isalso expressed as a T-score and as an estimate of the Bone Mineral Density (BMD, ing/cm2) of the calcaneus as measured by Dual Energy X-ray Absorptiometry (DXA).

3. Contraindications:

• The Sahara should not be used to assess patients whose skin is abraded and/or have anopen sore in the area that comes into contact with the system.

4. Warnings:

• Prior to using Sahara, users must read “Individualization of Treatment” and“Relationship between Sahara Results and Heel BMD Results obtained by X-RayDensitometry,“ below, in order to properly interpret patient results.

• Never attempt to operate the Sahara unit with any power module other than the oneprovided with the system (the Hologic Model Sahara Power Supply). The power supplyshould only be plugged into a wall outlet that meets all electrical code requirements.

• This equipment is not suitable for use in the presence of a flammable anesthetic mixturewith air or with oxygen or nitrous oxide.

Introduction 1


5. Precautions:

• Use the Sahara Advanced Clinical Bone Sonometer only indoors, in a clean, dryenvironment.

• Do not store the Sahara unit near a heat source or air conditioner. Store the phantom near theunit.

• Never store the QC phantom in the footwell with the transducer pads closed on it. This willruin both the phantom and the transducer pads.

• The Sahara Clinical Bone Sonometer provides no protection against the harmful ingress(entry) of liquids.

• If at any time the patient feels discomfort during use of the Sahara unit, the foot restraintmechanism is designed to allow the foot to be pulled out without having to operate anylevers or handles. The foot could also be removed by using the handles that fully release thefoot restraint mechanism. In addition, the Open/Prep button may be pushed at any time toopen the transducer pads. Note that in an emergency, it is not necessary to open the padsbefore removing the patient’s foot from the instrument.

• Only Hologic approved ultrasound coupling gels should be used with Sahara.• Sahara Ultrasound Coupling Gel is for external use only.• For ultrasound coupling gel application, do not use a Q-Tip, examination glove containing

talc, or any other applicator that may introduce fibers or other foreign matter.• When applying gel to the transducer pads, it is important to ensure that the leading edge of

the transducer pad is fully covered.• Interfacing equipment (computer, monitor, printer) used with the Sahara Clinical Bone

Sonometer must meet IEC 950, or equivalent safety standards.

6. Adverse Events:

There are no known potential adverse effects of the Sahara Clinical Bone Sonometer on health.

• Safety Experience and Sample Size: No adverse events of any kind were reported in thecourse of the clinical studies performed, in which a total of 2455 subjects underwent Saharaexaminations.

• Deaths: There were no patient deaths related to the Sahara Clinical Bone Sonometer eitherduring or after the clinical studies.

• Adverse Events: There were no adverse events related to the Sahara Clinical BoneSonometer either during or after the clinical studies.

• Adverse Events that may be expected: There are no known potential adverse effects of theSahara Clinical Bone Sonometer on health. Therefore adverse events are not expected inconjunction with the use of Sahara.

1 Introduction


7. Clinical Studies:

• Purpose of Studies: The clinical studies were designed to 1) directly compare estimated heelBMD results obtained on Sahara to those obtained on the established Dual Energy X-rayAbsorptiometry (DXA) technique, 2) assess the sensitivity of Sahara heel BMD results toskeletal status vs. that of DXA by comparing results obtained for clinically distinct groups ofyoung and elderly subjects, 3) assess the reproducibility of Sahara heel BMD results, 4)document the safety of the Sahara system, 5) obtain age dependent reference ranges forSahara estimated heel BMD results for a Caucasian female population, and 6) directlycompare Sahara results to those obtained by the Walker-Sonix UBA-575+ heel ultrasoundsystem, establishing the relationship between Sahara and fracture risk estimation.

• Patients Studied: Results for 247 Caucasian female subjects were obtained for the directcomparison of Sahara and DXA heel BMD results. Recruitment criteria were set to insurethat these subjects spanned the entire clinical range of heel BMD, with an approximatelyuniform distribution, in order to document the agreement between Sahara and DXA acrossthe entire useful range. Hip BMD results were used to classify elderly subjects using theinternationally accepted World Health Organization (WHO) criteria. Results for 2208subjects (age range 19-97) were obtained for development of reference ranges. Caucasianfemale subjects were chosen for these studies as they are the group most frequently affectedby osteoporosis.

• Methods: Heel BMD was estimated by Sahara for all subjects, including 5 replicatemeasurements for the 247 subjects in the comparative study. The 247 subjects from thecomparative study also underwent BMD assessment by DXA. Walker-Sonix heelultrasound results were obtained for 212 of the 247 subjects in the comparative study.

• Principal Effectiveness and Safety Results:

Objective ResultComparison of BMDResults vs. Heel DXA

Sahara Est. Heel BMD was linearly related to DXA Heel BMD(R=0.85).

ComparisonSensitivity to DXA

Sahara Est. Heel BMD essentially identical to Heel DXA orcomparisons of clinically distinct subject groups. Similar insensitivity to spine DXA.

Reproducibility ofHeel BMD

Est. Heel BMD reproducibility was found to be 3.0% in the 247subjects studied.

Document Safety No adverse events were observed (2245 subjects evaluated bySahara).

Reference Data Reference data ranges were developed based on 2208 Caucasianfemale subjects, and are included with standard Sahara system.

Comparison ofResults to Walker-Sonix UBA-575+

Sahara QUI and Est. Heel BMD results were linearly related toWalker-Sonix results (R=0.93). An relative risk of 1.84 for hipfracture was estimated for Sahara, based on published Walker-Sonix data.3

Introduction 1


8. Individualization of Treatment:

The Sahara Clinical Bone Sonometer estimates the Bone Mineral Density (BMD) of theheel. BMD results are used by the physician to assess skeletal status in the evaluation ofpatients at risk for osteoporosis and other metabolic bone diseases and/or patients whomay have reduced bone density due to medical conditions indirectly affecting bonemineral metabolism, medications prescribed for other conditions, heritable or geneticfactors, lifestyle factors, or other reasons. Heel BMD results may be used by thephysician, along with other factors such as laboratory test results, radiographs, and familyhistory, in the diagnosis of osteoporosis and other conditions leading to reduced bonedensity.

When evaluating individual patients, all relevant risk factors (including Sahara results,age, previous fractures, frame size, smoking, etc) should be considered. For additionalinformation, refer to the Physician Learning Series included with the Sahara system

The frequency of use of this device to assess BMD is dependent on a number of factors,including the precision of the device and the expected rate of loss or gain in BMD due todisease progression or therapeutic intervention, and must be determined by the physicianwho is aware of all of these factors. See Chapter 5, Patient Measurement for furtherinformation regarding monitoring of bone loss with Sahara.

Other than as indicated in the Contraindications and Warnings sections above, there areno specific populations for which Sahara should not be used. Guidelines for thedevelopment and use of reference ranges for populations other than Caucasian females(for which reference ranges are supplied by Hologic) are given in Chapter 6 of theAdvanced Clinical User’s Guide for the Sahara Clinical Bone Sonometer.

Relationship between Sahara Results and Heel BMD Results obtained by X-RayDensitometry

Sahara measures the speed of sound (SOS, in m/s) and broadband ultrasonic attenuation(BUA, in dB/MHz) of an ultrasound beam passed through the calcaneus (heel), andcombines these results linearly to obtain the Quantitative Ultrasound Index (QUI) and anEstimate of a patient’s heel BMD. While ultrasound parameters do not directly measureBMD, BUA and SOS results are correlated (R = 0.82 - 0.85) with heel BMD resultsobtained by the standard Dual Energy X-ray Absorptiometry (DXA) technique, as areresults for the combined QUI parameter (R=0.85). Thus an estimate of heel BMD resultsis obtained by a simple linear re-scaling of the QUI parameter into heel BMD units (ing/cm2). The level of correlation (R=0.85) between Sahara and DXA heel BMD results issimilar to that observed between other accepted methods for assessing BMD at the sameanatomical site.1 For individual patients, there may be differences between the Saharaand DXA Heel BMD results. These differences arise due to several factors, including theprecision errors inherent in both Sahara and DXA results as well as the subject dependentdifferences between the ultrasound and DXA measurement methodologies for assessing

1 Introduction


bone. For individual patients, differences between Sahara and DXA heel BMD resultshave a range equal to one standard deviation (SD) of a typical population of subjects ofthe same age. The 95% confidence interval for differences between Sahara and DXAheel BMD results is therefore ± 2 population SD’s, or ± 2 T-scores. This means thatindividual patients may be classified differently by Sahara compared to DXA when usingthe World Health Organization (WHO) classification criteria.2 The WHO criteria classifypatients with BMD values more than 2.5 SD’s below the young adult mean (T-scorebelow -2.5) as osteoporotic, and patients with T scores between -1 and -2.5 as osteopenic.However, the differences in T-score results obtained by Sahara and heel DXA are similarto or smaller than the differences found when patients are assessed by any other twoaccepted methods for assessing BMD of the same anatomical site.1 Note that differencesfor an individual patient when assessed at two different anatomical sites can be evenlarger due to physiological and anatomical differences between the various sites.1

It is widely accepted that while any measure of BMD is a strong indicator of risk forosteoporosis and osteoporotic fractures,3-5 classification by the WHO criteria is dependenton the measurement technique, and even more so on the measurement site. Thus anunderstanding of the potential differences in T-score results obtained by differenttechniques should be considered when applying the WHO classification criteria. Whenusing threshold based criteria to classify patients, the continuous exponential increase infracture risk with decreasing BMD (see Relationship Between Sahara Results and Risk ofFracture below) should be a factor in patient management decisions. Becauseosteoporosis is a multifactorial disease, consideration of all relevant risk factors isimportant in the evaluation of a patients. Other risk factors, besides BMD and T-score,include age, previous fractures, frame size, smoking, etc. For example, a 45 year oldpatient with a T-score of -2.7 and a 75 year old patient with the same T-score of -2.7 havedrastically different clinical status, and need to be evaluated appropriately. Similarly,there is no clinical distinction between two patients with T-scores of -2.49 and -2.51 ifthey have the same age and have no other risk factors. Other risk factors, besides T-scoreand age, include previous fractures, frame size, smoking, etc. See the Physician LearningSeries, included with the Sahara system for additional information.

9. Patient Counseling Information:

Patient Information Brochures are supplied with the Sahara system. These brochures give abrief summary of the importance of bone density testing and information about the SaharaClinical Bone Sonometer.

10. Conformance to Standards:

There are no known potential adverse effects of this device on health. In fact, this deviceuses ultrasound power levels lower than standard imaging ultrasound devices which arewidely used and accepted. No adverse events have been reported for the Sahara Clinical

Introduction 1


Bone Sonometer during clinical use, either from the clinical studies or from systemsinstalled internationally.

Non-clinical testing demonstrated conformance to voluntary safety (UL2601-1, EN60601-1-2 1993, CSA C22.2 No. 601-1-M90), electromagnetic compatibility (EN 55011Group I Class B, IEC 801-2 1991, IEC 801-3 1984, IEC 801-4 1988) and ISO (ISO9001) standards.

11. How Supplied:

The Sahara shipping package includes the following:

• One Sahara Ultrasound system

• One Power Supply and One Power cord

• One Positioning aide

• One QC Phantom

• Training Video (The Sahara User Video Guide)

• Starter supplies including: Sahara Ultrasound Coupling Gel (2 tubes) Transducer Towelettes (1 pkg) Dry wipes (1pkg) Pinter paper (2 rolls) Ultrasound exam paper (1pkg)

• Documents package containing:

User’s GuideSupplies reorder cardsInstallation, Warranty, and Post Warranty Service Information SheetQC Log Forms (1 tablet)Patient Report Forms (1 tablet)Patient Information Brochures (1 pkg)Sahara Physician Learning Series

• Sahara Advanced Clinical Software Package including:

One User’s Guide for the Sahara Advanced Clinical SoftwareOne Communications Cable (connects PC to Sahara system)Sahara Advanced Clinical Software (on Floppy Disk)

• One Personal Computer (PC) - if purchased from Hologic

12. Operator’s Manual:

Attached

1 Introduction


13. References:1 S. Grampp, H.K. Genant, A Mathur, P. Lang, M. Jergas, M. Takada, C.C. Gluer, Y.Lu, and M. Chavez, “Comparisons of Noninvasive Bone Mineral Measurements inAssessing Age-Related Loss, Fracture Discrimination, and DiagnosticClassification,” J. Bone and Miner. Res. Vol 12, pg 697-711, (1997).2 Kanis J, et al., Osteoporosis Int. Vol. 4, pg 368-381 (1994).3 Bauer DC, Gluer CC, Cauley JA, Vogt TM, Ensrud KE, Genant HK, Black DM.“Broadband ultrasound attenuation predicts fractures strongly and independently ofdensitometry in older women.” Archives of Internal Medicine Vol. 157, pg 629-633,(1997).4 Hans D, Dargent-Molina P, Schott AM, et al. “Ultrasonographic heel measurementsto predict hip fracture in elderly women: the EPIDOS prospective study.” LancetVol. 348, pg 511-4 (1996).5 Gluer CC, Cummings SR, Bauer DC, et al. “Osteoporosis: association of recentfractures with quantitative US findings.” Radiology Vol. 199, pg 725-32 (1996).

Quantitative Ultrasound (QUS) as a Tool for theAssessment of Bone Status

Ultrasound is well established in the medical community as a safe and cost effectivediagnostic modality. Until recently, medical ultrasound has primarily given clinicians onlyqualitative images of soft tissue. However, it is also possible to use ultrasound to obtainquantitative information about bone status. In comparison to traditional techniques forassessment of skeletal status (including radiographs, x-ray absorptiometry, and computedtomography) which involve exposure to radiation, QUS is a quick, low cost, and radiationfree diagnostic tool. These advantages are especially important in the clinicalenvironment for which Sahara was designed, where unnecessary operator and patient x-ray exposure (for example) are undesirable.

Many bone diseases, including osteoporosis, degrade cancellous (or trabecular) bonemuch earlier and to a greater extent than cortical bone. Turnover of cancellous bone isabout eight-fold higher than of cortical bone, thus age and disease related bone loss aremore readily apparent in cancellous bone compartments. Therefore, it is becoming morewidely accepted in the medical community that skeletal sites with a high percentage ofcancellous bone are important examination sites for patients at risk for osteoporosis andother metabolic bone diseases. The calcaneus (heel), a bone that is 75-90% cancellousbone by volume and is readily accessible because of the small amount of soft tissuesurrounding it, is particularly attractive for studies aimed at the identification and/orassessment of patients at risk. QUS is a modality particularly well suited for theexamination of cancellous bone of the heel.

Introduction 1


QUS results obtained using the Sahara system are correlated to heel Bone MineralDensity (BMD, in g/cm2) results obtained by Dual energy X-ray Absorptiometry (DXA),the most widely used technique for assessing BMD. Thus Sahara ultrasound results can beconverted into DXA equivalent units (g/cm2) in order to be more easily interpreted byphysicians. The Sahara system therefore reports the “Estimated BMD” of the heel ing/cm2 as the default output result. Because this Estimated BMD was obtained fromultrasonic measurements, the ultrasound results may also be displayed if desired. Accessto the underlying ultrasound measurement results is especially important for Saharasystem Quality Control, where monitoring of the ultrasound parameters is critical fortracking of system performance.

Sahara Advanced Clinical System OverviewThe Sahara Advanced Clinical Bone Sonometer consists of a portable medical device (theSahara “Clinical” Bone Sonometer) that when combined with the optional “AdvancedClinical” Software and an external computer provides a Microsoft Windows®-basedworkstation and full graphics printer. The Hologic Sahara Advanced Clinical SoftwareOption, installed on the external PC, provides a data base for storage and retrieval ofpatient records. For operator convenience, the instrument may be controlled using amouse from the computer, rather than by pressing the keys on the Sahara unit. In addition,full size patient reports including patient history can be obtained. This software optionmay be installed at any time before or after system installation, as each Sahara system hasa standard communication port installed at the factory for communication with theoptional Advanced Clinical Software/computer. The system may be used either with orwithout the external computer at any time, so long as it is understood that the computermust be connected prior to any patient examination for which the operator wishes that theresults be stored in the computer database. If the computer is disconnected, the SaharaClinical System operates exactly the same as the standard system without the AdvancedClinical Software Option.

Sahara measures the ultrasonic Speed Of Sound (SOS) and Broadband UltrasoundAttenuation (BUA) of the calcaneus (heel), and combines these two measured values toobtain a parameter referred to as the Quantitative Ultrasound Index (QUI), sometimesreferred to as “stiffness” in the scientific literature. The QUI/Stiffness value obtained for apatient is then converted into Estimated BMD (in units of g/cm2) in order to simplify theinterpretation of results by the physician. Estimated BMD results may be compared toUS Caucasian female reference values, or to user defined reference values (if available)for other populations, in order to assess the bone status of the patient relative to sex andrace matched norms.

The measurement is taken with the patient seated and their foot positioned and secured inthe Sahara system. Soft rubber pads are brought into contact with either side of the heel,and the measurement is performed by passing sound waves through the heel. Anultrasound coupling gel is used between the pads and the patient’s skin. No water bath is

1 Introduction


necessary, and the entire procedure (including patient positioning) takes only a fewminutes. Note that the use of coupling gel is critical because it eliminates air at theinterface between the pads and the skin, which would otherwise severely inhibit thetransmission of sound waves.

To ensure proper operation, use only the couplant gel provided by Hologic (labeled“Sahara Ultrasound Coupling Gel”). Other gels, particularly those that are water based,will adversely affect system performance, giving inaccurate and/or inconsistent results.

The system design provides for a highly repeatable method of positioning the foot withrespect to the measurement device. The lower leg is immobilized by a positioning aidfitted with moldable foam, and a padded strap secures the leg into the positioning aid toset the proper leg angle.

Ultrasound Measurements Using SaharaThe term ultrasound refers to high-frequency (non-audible) sound waves. Ultrasoundmeasurements are made on the Sahara system by measuring the transmission of thesesound waves through the heel. The heel is positioned between a pair of sound transducers(Fig 1-2), with one transducer transmitting the ultrasound signal, and the other transducerreceiving the signal after passage through the heel. The transducers are acousticallycoupled to the heel by elastomer transducer pads using Sahara Ultrasound Coupling gel,which is applied to the transducer pads. From the signal measured by the receivingtransducer, two parameters describing the nature of the received sound waves can besimultaneously determined: Speed of Sound (SOS) and Broadband Ultrasonic Attenuation(BUA).

Figure 1-1Sahara Advanced

Clinical System

Introduction 1


Speed Of Sound (SOS)SOS is defined as the speed of sound through the heel. SOS is determined (Fig. 1-3) bymeasuring (1) the width of the heel, and (2) the time delay between the initialtransmission of the sound waves (by one transducer) and the receipt of the sound waves(by the second transducer). The Sahara system measures and corrects for the time delayincurred by the sound waves as they travel through the transducer pads by making asimilar measurement without the heel (i.e., with the two pads touching one another) inorder to determine the time delay due to the heel alone. The time (t) the ultrasound signaltakes to go through the heel alone is the propagation time of the ultrasound going throughthe heel and the transducer pads minus the propagation time measured with the padstouching and with no heel interposed. Sahara automatically measures the width of the heel(w) using a micrometer attached to the transducers. The SOS value is then equal to w/tand is measured in meters per second (m/s). The range observed with Sahara in a typicalpopulation is approximately 1450-1700 m/s, with young/healthy subjects having higherSOS values than older or osteoporotic subjects.

Figure 1-2Sahara Measurement

Geometry

1 Introduction


Broadband Ultrasound Attenuation (BUA)During early investigations of bone with QUS, it was observed that bone attenuated highfrequency sound waves much more than low frequency sound waves. A linear relationship(Fig. 1-4) was observed for the attenuation (in decibels, or dB) of ultrasonic waves in thefrequency range of 0.2 to 0.6 MHz. The slope of the linear regression of the ultrasonicattenuation vs. frequency in this range is defined to be the broad-band ultrasoundattenuation (BUA) and is measured in dB/MHz. On the Sahara system, the BUA and SOSare measured at the same time. As is the case for the SOS measurement, in order todetermine the attenuation of the heel alone, and remove any effects arising from thetransducers and/or transducer pads, a comparison measurement must be made through areference medium. This reference measurement is made using the Sahara QC Phantom(supplied with the Sahara unit) when the unit is calibrated at the factory.* The range ofBUA observed with Sahara in a typical population is approximately 30-130 dB/MHz,with young/healthy subjects having higher BUA results than older or osteoporoticsubjects.

*Note: In the course of typical usage, it is not necessary to perform a referencemeasurement/calibration. However, if the transducer pads,transducers, or electronics are removed or disassembled for anyreason, the unit must be re-calibrated following the instructions in theMaintenance chapter of this manual.

Figure 1-3SOS Measurement

Introduction 1


Estimated Heel BMD and the Quantitative Ultrasound Index(QUI)

In order to optimize the quantitative information obtained by both BUA and SOSmeasurements, the Sahara system combines (linearly) the two measured values into asingle parameter, the Quantitative Ultrasound Index (QUI), sometimes referred to as“Stiffness” in the scientific literature. Compared to the BUA or SOS parameters alone, thecombined QUI parameter is both more strongly correlated to the actual heel BMDobtained by the DXA, and also has a reduced precision error. QUI values normally rangefrom 0 to 150, with higher values being obtained for young healthy subjects, and lowervalues being obtained for older or osteoporotic subjects.

Because the QUI parameter is correlated to heel (DXA) BMD results, a predicted or“Estimated” heel BMD result may be obtained by a simple re-scaling of the QUI value.Thus the re-scaled QUI value (“Estimated Heel BMD, in g/cm2) is reported by the Saharasystem as the default output parameter. Note that the QUI is a simple linear combinationof the BUA and SOS, which is formed merely to improve the estimate of heel BMD, thedefault output of the Sahara system.

Relationship of Sahara Results and Heel BMD Resultsobtained by X-Ray Densitometry

Clinical studies have compared Sahara results to heel BMD assessed using the establishedDual Energy X-Ray Absorptiometry (DXA) technique. These studies have shown thatBUA and SOS, the parameters directly measured by Sahara, are correlated (R = 0.82 -0.85) with DXA BMD. Sahara QUI and Estimated Heel BMD values are also correlated(R=0.85) to DXA BMD results. This level of correlation is similar to that observedbetween other accepted methods for assessing BMD at the same anatomical site. For

Figure 1-4BUA Measurement

1 Introduction


example, published studies have shown that standard posteroanterior (PA) DXA lumbarspine BMD results and spine BMD results obtained by the quantitative computedtomography (QCT) technique have in vivo correlations of 0.83.1

The relationship between Sahara and DXA heel BMD results is linear, with the averageBMD values (for a group of subjects) obtained by either technique being clinicallyindistinguishable. For individual patients, however, there may be differences between theSahara Estimated Heel BMD and the DXA Heel BMD. These differences arise due toseveral factors, including the precision errors inherent in both Sahara and DXA results aswell as the subject dependent differences between the ultrasound and DXA measurementmethodologies for assessing bone. Subject dependent differences between Sahara andDXA heel BMD results have a range equal to one standard deviation (SD) of a typicalpopulation of subjects of the same age. The 95% confidence interval for differencesbetween Sahara and DXA heel BMD results is therefore ± 2 population SD’s. T-scores,which quantify the difference between a given patient’s results and the mean results for ayoung adult reference group, are reported in population SD units. Thus patients assessedby Sahara and heel DXA will have results that are equal on the average, but that differ byup to ± 2 T-scores for an individual patient. This means that individual patients may beclassified differently by Sahara compared to DXA when using the World HealthOrganization (WHO) classification criteria.2 The WHO criteria classify patients withBMD values more than 2.5 SD’s below the young adult mean (T-score below -2.5) asosteoporotic, and patients with T scores between -1 and -2.5 as osteopenic. However, thedifferences in T-score results obtained by Sahara and heel DXA are similar to or smallerthan the differences found when patients are assessed by any other two accepted methodsfor assessing BMD of the same anatomical site.1 For example, the 95% confidenceinterval is ± 1.8 T-scores for DXA vs. QCT of the spine. Furthermore, the differences foran individual patient assessed at two different anatomical sites can be even larger due tophysiological and anatomical differences between the various sites.1

It is widely accepted that while any measure of BMD is a strong indicator of risk forosteoporosis and osteoporotic fractures, classification by the WHO criteria is dependenton the measurement technique, and even more so on the measurement site. Thus anunderstanding of the potential differences in T-score results obtained by differenttechniques should be considered when applying the WHO classification criteria. Whenusing threshold based criteria to classify patients, the continuous exponential increase infracture risk with decreasing BMD (see Relationship Between Sahara Results and Risk ofFracture below) should be a factor in patient management decisions. Becauseosteoporosis is a multifactorial disease, consideration of all relevant risk factors isimportant in the evaluation of a patients. Other risk factors, besides BMD and T-score,include age, previous fractures, frame size, smoking, etc. For example, a 45 year oldpatient with a T-score of -2.7 and a 75 year old patient with the same T-score of -2.7 havedrastically different clinical status, and need to be evaluated appropriately. Similarly,there is no clinical distinction between two patients with T-scores of -2.49 and -2.51 ifthey have the same age and have no other risk factors. Other risk factors, besides T-score

Introduction 1


and age, include previous fractures, frame size, smoking, etc. See the Physician LearningSeries, included with the Sahara system for additional information.

1 S. Grampp, H.K. Genant, A Mathur, P. Lang, M. Jergas, M. Takada, C.C. Gluer, Y. Lu,and M. Chavez, “Comparisons of Noninvasive Bone Mineral Measurements in AssessingAge-Related Loss, Fracture Discrimination, and Diagnostic Classification,” J. Bone andMiner. Res. Vol 12, pg 697-711, (1997).2 Kanis J, et al., Osteoporosis Int. Vol. 4, pg 368-381 (1994).

Relationship between Sahara Results and Risk of FractureIt has been demonstrated in a number of large, multi-center, prospective clinical studiesthat subjects with low BMD are at higher risk of fracture.3-5 These studies have foundthat for elderly Caucasian female subjects (age greater than 70) the risk of future fractureincreases exponentially with decreasing BMD. For hip fractures, for example, it wasfound that for each population standard deviation (SD) decrease in hip BMD, there was a2 to 3-fold increase in the incidence of fracture. Note that a 2-fold increase in fracturerisk per population SD decrease in BMD is referred to as “a relative risk of 2.0.” Therelative risk result is computed in terms of the difference (in population SD units)between a patient’s results and the age matched mean value, which is equivalent to thepatient’s Z-score. That is, if the relative risk is 2, then a patient with a Z-score of -1 hastwice the risk of hip fracture compared to a patient with a Z-score of 0. A patient with aZ-score of -3 has 8 times (2 to the third power) the risk of hip fracture.

The data from the fracture risk studies demonstrates that there is a “gradient of risk,”which means that the risk of fracture increases continuously with decreasing BMD. Thisis in contrast to the “threshold” concept, in which risk suddenly increases below a specificBMD threshold value. Because the results of these and many other studies are consistentwith a gradient of risk rather than with a threshold, care must be taken when applyingthreshold based classification criteria such as those proposed by the WHO. Nonetheless,threshold based guidelines and decision making are in fact commonplace in medicalpractice even in similar situations (cholesterol testing for example), but should be appliedwith the understanding that risk is continually increasing above and below the threshold.

The studies found that a similar relationship to hip fracture risk existed for heelultrasound results, with approximately a 2-fold increase in risk per population SD. Inparticular, one of the studies included both x-ray based and ultrasound measurements ofthe heel, and found essentially identical results: the relative risk values for heelultrasound and heel x-ray BMD were 2.0 and 2.2 respectively.3 For these studies, heelultrasound results were obtained using ultrasound systems that use a water bath to couplesound waves to the heel. Sahara is a “dry” heel ultrasound system that uses soft elastomerpads and an ultrasound gel to couple sound to the heel, but is otherwise similar to the“wet” systems used in the fracture risk studies. Data comparing the Sahara and the

1 Introduction


Walker-Sonix UBA-575+ (the system used in one of the fracture studies) was obtained inthe Sahara clinical study. This comparative data demonstrates the strong linearrelationship (R=0.93) between Sahara and Walker-Sonix results, which in turn suggeststhat Sahara results are sensitive to risk of future fracture. In order to estimatequantitatively the sensitivity of Sahara results to risk of fracture, the data from Bauer, etal.3 were re-analyzed, after using the Walker-Sonix heel ultrasound results to predictSahara results for all study subjects. In this analysis, Sahara results were estimated usingthe slope, intercept, and RMSE describing the relationship between Sahara and Walker-Sonix results, as determined in the Sahara clinical study. The estimated Sahara results forall study subjects were then analyzed in exactly the same manner as for the original studydata, resulting in a relative risk value of 1.84. Receiver-operator-characteristic (ROC)curves were constructed, indicating that there were no clinically significant differencesbetween the discriminatory abilities of Sahara and Walker-Sonix results.

In summary, large prospective studies have thus demonstrated the strong exponentialrelationship between heel ultrasound and x-ray results and the risk of fracture. The strongrelationship between Sahara and Walker-Sonix results suggests that Sahara results will beequally predictive of fracture risk. For additional information, see the Physician LearningSeries included with the Sahara system.3 Bauer DC, Gluer CC, Cauley JA, Vogt TM, Ensrud KE, Genant HK, Black DM.“Broadband ultrasound attenuation predicts fractures strongly and independently ofdensitometry in older women.” Archives of Internal Medicine Vol. 157, pg 629-633,(1997).4 Hans D, Dargent-Molina P, Schott AM, et al. “Ultrasonographic heel measurements topredict hip fracture in elderly women: the EPIDOS prospective study.” Lancet Vol. 348,pg 511-4 (1996).5 Gluer CC, Cummings SR, Bauer DC, et al. “Osteoporosis: association of recentfractures with quantitative US findings.” Radiology Vol. 199, pg 725-32 (1996).

System ComponentsThe key components of the Sahara Advanced Clinical Bone Sonometer system, shown inFigure 1-5, include the ultrasound unit (including positioning aid), power supply, powercord, QC phantom, Sahara Ultrasound Coupling Gel, and an external desktop or laptopWindows-based PC (not shown). The PC functions as a remote controller, data basemanager and data storage device for the ultrasound system.

A complete list of accessories and supplies for the Sahara system with the AdvancedClinical Software option is given in the Essential Prescribing Information above, and alsoin Chapter 2 of this User’s Guide.

Introduction 1


Sahara External Computer SpecificationsThe computer (PC) used with the Sahara Research System must meet the followingminimum specifications. The PC may be a desktop or a laptop (with either a color ormonochrome display). Computers with more memory, larger disks, and faster processorsare allowed, and are likely to improve performance of the system.

Processor: 80486

Co-Processor: recommended, but not required

CPU Speed: 33 Mhz

RAM: 8 MB

Display: 640 by 480 by 16 greyscale

Hard Disk: 100 MB

Floppy: 3.5”, 1.44 MB

Serial port: COM STD, 16550 UART or equivalent high speed

Parallel port: Printer (Centronics) standard

Windows Version: 3.1 or Win95

Safety Rating: IEC 950 or equivalent

Figure 1-5System

Components

1 Introduction


There are no controller boards to add to the computer. All communication between theSahara and the computer takes place over a standard serial port and cable. (RS232connection). One end of the cable plugs into the Sahara serial port connector and theother end plugs into the computer’s COM1 or COM2 serial port connector.

The serial cable is provided with the Advanced Clinical Software. This communicationcable (Hologic PN 180-0318) is an industry standard PC to PC null modem cable with 9pin D female connectors on each end. For older computers with only a 25-pin Dconnector, adapters are readily available wherever computers are sold.

The Advanced Clinical Software is supplied on 3.5 inch disks, along with an automaticinstallation program.

Quality Control (QC) PhantomThe QC phantom supplied with the Sahara system serves two distinct purposes:

1. Daily measurements of SOS and BUA using this phantom allows monitoring ofsystem performance over time. See the Quality Control chapter, in this manual, formore information.

2. The QC phantom is used to calibrate the Sahara system for BUA and SOSmeasurement in the event of malfunction, or if the transducers, transducer pads, orelectronics are removed or replaced for any reason.

Note: The QC phantom should be stored with the unit but not in the heel well.The phantom and pads can both be ruined by long term contact witheach other.

Ultrasound Coupling gelThe Sahara Clinical Bone Sonometer requires the use of a special couplant gel that issupplied with the unit. Standard ultrasound coupling gel will not provide the specifiedperformance level. To ensure proper operation, use only the couplant gel provided byHologic (labeled “Sahara Ultrasound Coupling Gel”). Other gels, particularly those thatare water based, will adversely affect the measurement results. Information on orderingSahara Ultrasound Coupling Gel can be found in the System Care and Maintenancechapter of this manual.

Introduction 1


Controls and IndicatorsThis section describes the controls and indicators on the Sahara Control Panel.

The power status light is located at the rear of the instrument near the power connection.This light will illuminate when power is applied to the unit. Note that the Saharainstrument does not have an on/off switch. Power is applied by plugging in the powermodule.

The Control Panel, shown in Figure 1-7, contains a display screen, numeric keypad andfive functional switches.

Figure 1-6Power Status Light

Figure 1-7Control Panel

Program

Enter

On Open/Prep

MeasurePrint/Feed

� � �

�

�

��

�

�

0

�

+/-

1 Introduction


Table 1-1 describes the functions on the Sahara Control Panel.

Table 1-1Control Panel

Control Description

Numeric Keypad The Numeric Keypad consists of the numbers 0 through 9, theProgram and Enter buttons. These are used to enter phantominformation and other numeric data. The Numeric Keypad is notnormally used during patient measurements.

LCD Screen The LCD display screen displays messages to prompt the user througha measurement, and displays the result of a measurement.

ON Button This button takes the system out of standby mode, or initializes thesystem to prepare for a new measurement.

OPEN/PREP Button This button places the transducer pads in the Open (fully open), orPrepare (half open), positions, and may be used to open the padsanytime they are closed, or are closing.

MEASURE Button This button commands the system to close the transducer pads andperform an ultrasound measurement.

PRINT/FEED Button This button commands the system to print the current results oradvance printer paper if the optional line printer is supplied.

Program Button This button is used to inform the Sahara that program information(such as setting time and date) will follow.

ENTER Button This button is used to initiate functions entered with the PROGRAMand Numeric Keypad.

+/- Button This button allows the user to toggle between Estimated BMD resultsand QUI/BUA/SOS results after a measurement. It is also used in thePROGRAM mode to alter numeric sign and select choices.

Introduction 1


SpecificationsIEC 601-1 Class 1 Type BF. IPX0. The UL classification for the Sahara Clinical BoneSonometer is Class 1 Equipment. Table 1-2 lists the specifications for the Sahara clinicalsystem.

Table 1-2Sahara Specifications

Measurement Site: Calcaneus (heel)

Coupling Method: Sahara Coupling Gel only

Measurement Time: less than 10 seconds

Patient Reports: Built-in Strip Printer

Measurement Results: Estimated Heel BMD and Quantitative Ultrasound Index(QUI), obtained from measured BUA and SOS

Estimated Heel BMDC.V.:Absolute Precision:

3%0.014 g/cm2

QUIC.V.:Absolute Precision:

2.6%2.2

SOSC.V.:Absolute Precision:

0.22%3.4 m/s

BUAC.V.:Absolute Precision:

3.7%2.6 dB/MHz

QC Check: Daily, utilizing supplied QC phantom

Operating temperature range: 60° - 100° F (15° - 37.7° C)

Operating humidity range: 20-80% R.H. non condensing

Shipping and Storage:Ambient TemperatureRelative HumidityAtmospheric Pressure

0° to 120° F (-17.8° C to 49° C)20% to 95%500 hPa to 1060 hPa

Power Requirements: 100-240 VAC, 50-60 Hz, <60 watts (automatically adjustsfrom 100 VAC to 240 VAC, and 50 Hz to 60Hz)

CPU Embedded microprocessor

Ultrasonic Energy: Isppa < 0.001 W/ cm2 typicalIspta < 0.001 mW/ cm2 typicalMechanical Index (MI) < 0.01 typicalPulse Repetition Rate (PRR) < 200 Hz

Safety Standards: IEC601-1, UL2601-1, CSA C22.2

Size: 17"D x 14"W x 12"H (43cm x 36cm x 30cm)

Weight: 22 lb. (10 kg)

1 Introduction


Initial Set Up 2

Clinical User’s Guide 2-1

2 Initial Set Up

This chapter describes how to set up the Sahara Clinical Bone Sonometer. It coversexamination room requirements, unpacking, system set up, and printer operation.

Examination Room EnvironmentHologic recommends a clean, dry examination room, with the temperature of the roommaintained between 65° and 75° F (20° and 27° C). If possible, store the Sahara in thesame room used for patient measurement (to minimize temperature changes to theinstrument). Do not store the unit near a heat source or air conditioner. Store the phantomnear the unit.

Note: Never store the QC phantom in the footwell with the transducer padsclosed on it. This will ruin both the phantom and the transducer pads.

The exam room should have a standard electrical outlet, and a stationary (not rocking orgliding) straight back chair for the patient. The patient chair should have arms for patientcomfort and a seat height of approximately 16 to 18 inches (41 to 46 cm) from the floor.The Sahara operator should be seated on a low height stool such as an exam stool.

Unpacking the SystemFigure 2-1 shows the key components of the Sahara Clinical Bone Sonometer. Refer tothe figure, and the list below it, to insure that all items were received.

2

2 Initial Set Up


The Sahara shipping package includes the following:

• Sahara system• Power Supply and Power Cord• Positioning Aid• QC Phantom• Training Video (Sahara User Video Guide)• Starter supplies including:

Sahara Ultrasound Coupling Gel (2 tubes) Transducer Towelettes (1 pkg) Dry wipes (1pkg) Pinter paper (2 rolls) Ultrasound exam paper (1pkg)

• Documents package containing:User’s GuideSupplies reorder cardsInstallation, Warranty, and Post Warranty Service Information SheetQC Log Forms (1 tablet)Patient Report Forms (1 tablet)Patient Information Brochures (1 pkg)Sahara Physician Learning Series

To unpack the system, follow the procedure below.

Figure 2-1Unpacking the System

Initial Set Up 2


1. Remove the top tray containing the Power Supply, QC Phantom, Training Video,starter supplies, and documents package.

2. Remove the foam packaging material that covers the top of the system.

3. Remove the positioning aid (wrapped in packaging material and located on thesystem).

4. Carefully remove the system from the box by its handle, and take the system out ofthe plastic bag.

5. Locate the power supply and power cord and unwrap.

Note: The box and packing materials should be saved in case the systemhas to be transported elsewhere, or returned for service, at somefuture date.

Setup and TestThis section describes how to set up and test the Sahara Clinical Bone Sonometer.

Power On the SystemFollow the procedure below to complete the initial set up and test of the system.

1. Place the system on the floor where it will be used.

2. Plug the power supply into the system (the figure below shows the power supplyconnections).

Figure 2-2Power Supply

Connections

2 Initial Set Up


3. Plug the power supply into the wall outlet. The green power status light, located nearthe power connection, will illuminate.

Note: Always perform Steps 2 and 3 in this order to avoid damaging the unit.

4. The Control Panel Screen initially displays:

HOLOGIC **Sahara**Version x.y

Followed by:

Power On Self Test:In Progress…

5. Upon completion of the self test, the Control Panel Screen displays:

Power On Self Test:Passed

OR

Figure 2-3Power Status Light

Initial Set Up 2


Power On Self Test:Failed

The above messages will be displayed anytime the system is plugged in after beingunplugged.

If the Power On Self Test fails, see the System Malfunction section in Chapter 6 ofthis manual.

6. When the Self Test passes, the Control Panel Screen displays:

Press ON

7. Press ON to initialize Sahara. The Control Panel Screen displays:

Initializing…

Then:

Gel PadsPress OPEN

2 Initial Set Up


Printer OperationFollow the procedure below to load printer paper:

1. Remove the printer cover by sliding the cover towards the rear.

2. Grasp the paper roll in your hand and feed the paper through the printer as shown inStep 1 of Figure 2-5 and Figure 2-6. Insert the paper into the paper slot where arrowsindicate. The paper should feed from the underside of the roll.

3. To feed the paper press the PRINT/FEED button while the display screen isdisplaying “Gel Pads press OPEN”.

Figure 2-4Removing Printer Cover

Figure 2-5Threading Printer

Paper

Initial Set Up 2


4. Place the paper roll into the printer tray. Insert the paper roll in the tray as shown inFigure 2-7 and Step 2 of Figure 2-5.

Figure 2-6Feed Printer Paper

Figure 2-7Insert Paper Roll

2 Initial Set Up


5. Insert the paper through the slot in the printer cover and reinstall the cover.

Note: Never pull the paper (either forwards or backwards) through the printer.Always advance the paper using the Print/Feed button, and tear off usingthe cover slit.

Figure 2-8Printer Cover Replaced

Initial Set Up 2


Set TimeTo set the time in your Sahara system, follow the procedure below:

1. Press ON. The Control Panel Screen displays the following.

Gel PadsPress OPEN

2. To set the time, press PROGRAM, 9, ENTER. The Control Panel Screen displaysthe time (in 24 hour format).

Time - XX:XX1) Change 2) Exit

3. If the time displayed is correct, press 2.

4. If the time displayed is incorrect, set the correct time as follows:

5. Press 1. The Control Panel Screen displays the following:

Figure 2-9Press Program, 9,

ENTER

Program

Enter

On Open/Prep

MeasurePrint/Feed

1 2 3

4

7

��

5

8

0

6

9

+/-

2 Initial Set Up


Time - 11:15Hour: 0

6. Insert the hour in 24 hour format, then press ENTER. The Control Panel Screendisplays the following:

Time - 11:15Minute: 0

7. Insert the minute, then press ENTER. The Control Panel Screen displays thefollowing (XX:XX represents the time you set):

Time - XX:XX1) Change 2) Exit

8. Press 2 to set the time as shown, or press 1 to start over.

9. After the time has been set, the Control Panel Screen displays:

Gel PadsPress OPEN

Initial Set Up 2


Set DateTo set the date, in your Sahara system, follow the procedure below:

1. Press ON. The Control Panel Screen displays the following:

Gel PadsPress OPEN

2. To set the date, press PROGRAM, 8, ENTER. The Control Panel Screen displaysthe date.

Date - 2/17/19971) Change 2) Exit

3. If the date displayed is correct, press 2.

4. If the date displayed is incorrect, set the correct date as follows:


Date - 2/17/1997Month: 0

Figure 2-10Press PROGRAM, 8,

ENTER

Program

Enter

On Open/Prep

MeasurePrint/Feed

1 2 3

4

7

��

5

8

0

6

9

+/-

2 Initial Set Up


6. Insert the month, then press ENTER. The Control Panel Screen displays thefollowing:

Date - 2/17/1997Day: 0

7. Insert the day, then press ENTER. The Control Panel Screen displays the following:

Date - 2/17/1997Year: 0

8. Insert the year, for example “1997”, then press ENTER. The Control Panel Screendisplays the following (XX/XX/XXXX represents the date you set):

Date - 2/17/19971) Change 2) Exit

9. Press 2 to set the date as shown, or press 1 to start over.

10. After the date has been set, the Control Panel Screen displays:

Gel PadsPress OPEN

Note: Time and date may be set whenever the “Gel Pads Press OPEN” or“Gel Pads for QC Press OPEN” screens are displayed.

Initial Set Up 2


Set LanguageYou may now can choose between different languages to be used on the SAHARAdisplay. Use the following procedure:

1. Press Program on the SAHARA keypad.

2. Press 4 on the SAHARA keypad.

3. Press 2 on the SAHARA keypad.

4. Press Enter on the SAHARA keypad.

5. Press 9 on the SAHARA keypad

6. Press 8 on the SAHARA keypad

7. Press Enter on the SAHARA keypad. The language menu will appear on the display

English ?1) Yes 2) No

By continually pressing 2 (No) you can cycle through the following languages:

ENGLISH PORTUGUESE

ITALIANO DEUTSCH

FRANCAIS SLOVIK

ESPANOL CROATIAN

8. At any time you press 1 (Yes), the SAHARA will use that language on its display andin its printouts. The program returns you to the Gel Pad menu displayed in theselected language:

Gel PadsPress OPEN

Notes: 1. If you cycle through all the languages by press 2 (No), after theCROATIAN language selection you will be returned to the GelPad menu.

2. The major display modes (as well as the SAHARA report printouts) will betranslated into the selected language. Error messages appear in the Englishlanguage at this time.

2 Initial Set Up


Quality Control 3


3 Quality Control

This chapter describes how to perform the Quality Control (QC) procedure on the SaharaClinical Bone Sonometer.

Each Sahara is supplied with a Quality Control phantom to monitor system performanceover time. It is recommended that a QC phantom measurement be performed each day,prior to using the system to measure patients. However, it is acceptable for the QCmeasurement to be performed after patients are measured if the system and phantom arenot at the same temperature as described in the note below.

Note: Always store the QC phantom near the Sahara system. BUA and SOSreadings for the phantom are temperature dependent, and may vary ifthe phantom and system are not maintained at the same (room)temperature. Thus it is important that the phantom be kept near thesystem so that they are at the same temperature. If the phantom has notbeen kept in the same location, allow one hour for the temperature ofthe phantom to stabilize before using the phantom for calibration orQC. Never store the phantom in the unit footwell with the pads closedon it, as this will destroy both the pads and the phantom.

Because the variation of the ultrasonic properties of the phantom due to temperature arelarger than the Sahara unit’s short and long term precision, QC results provide aconservative estimate of the performance of the Sahara system. It is common to observefluctuations in QC results within the normal acceptable range defined by the dashed lineson the Quality Control Log forms (see below). Occasionally, QC results will be outsideof these ranges, and repeating the QC procedure after 1 hour will give acceptable resultsdue to the stabilization of the phantom temperature. In addition, Sahara alsoautomatically identifies QC results that are far enough outside of the acceptable range asto indicate either a procedural error (no gel used, for example) or a system malfunction.In such a case, the system displays a “QC Failed” message, and the system should not beused to evaluate patients until an acceptable result is obtained or the unit is serviced.

The remainder of this chapter describes the procedure for performing QC measurementsand guidelines for interpreting results. QC measurement consists of initializing thesystem, applying gel to the pads, opening the pads, positioning and securing the QC

3

3 Quality Control


phantom in the system, performing the measurement, printing the measurement results,removing the phantom from the system, and cleaning the phantom and the pads.

QC results may be plotted as a function of time using the Quality Control Log sheetsdescribed in the section titled Recording/Plotting QC Results, in this chapter. The QCLog sheets will allow recording and plotting of QC results, with one month of QC datarecorded on each sheet.

Quality Control ProcedureTo perform QC, follow the procedure below.

1. Press the ON button. The system initializes itself and closes the transducer pads untilthey touch, and then opens them for gel application.

Figure 3-1Press ON

Program

Enter

On Open/Prep

MeasurePrint/Feed

1 2 3

4

7

��

5

8

0

6

9

+/-

Quality Control 3


Note: If there is no operator action within ten minutes after ON is pressed,the unit goes to Power Saver Mode (the screen goes blank). Pressthe ON key to return to the last screen.

2. Press the PROGRAM button on the keypad, then press the 1 button, and then pressENTER. This tells the system that a QC measurement is about to be made.

Figure 3-2Transducer Pads Touch

Figure 3-3Transducer Pads Ready

for Gel

3 Quality Control


The Control Panel Screen displays:

Gel Pads for QCPress OPEN

3. For each transducer pad, squeeze out about a one inch (2.5 cm) bead of gel onto yourfinger (see the figure below).

Note: Do not use a Q-Tip, examination glove containing talc, or any otherapplicator that may introduce fibers or other foreign matter.


ENTER

Program

Enter

On Open/Prep

MeasurePrint/Feed

1 2 3

4

7

��

5

8

0

6

9

+/-

Quality Control 3


Figure 3-5Gel Measurement

Figure 3-6Spread Gel

3 Quality Control


4. Apply gel evenly on the face of the pad.

Note: It is important that the leading edge of the transducer pad is fullycovered.

5. When gel has been applied to both transducer pads press the OPEN/PREP button.The scanner opens the transducer pads to the fully open position.


Figure 3-7Proper Amount of Gel

on Transducer Pad

Figure 3-8Press OPEN/PREP

Program

Enter

On Open/Prep

MeasurePrint/Feed

1 2 3

4

7

��

5

8

0

6

9

+/-

Quality Control 3


Insert PhantomPress MEASURE

6. Place the QC phantom in the Sahara. Position the phantom so that its rounded end issnugly in the positioning contour (heel cup), and the label is on top.

7. Press the MEASURE button. The scanner performs the measurement, thenautomatically opens the transducer pads.

Figure 3-9QC Phantom Position

3 Quality Control


8. The Control Panel Screen displays the following. Remove the QC phantom.

Remove Phantom1) Press PREP 2) Clean

9. Press OPEN/PREP. The transducer pads return to the ready position.

10. Carefully clean and dry the phantom and the transducer pads. Use towelettes suppliedin the Accessories Kit to clean the phantom and transducer pads, and dry wipes to drythem.

11. If the QC test is within limits the display screen will display:

Figure 3-10Press MEASURE

Program

Enter

On Open/Prep

MeasurePrint/Feed

1 2 3

4

7

��

5

8

0

6

9

+/-


Program

Enter

On Open/Prep

MeasurePrint/Feed

1 2 3

4

7

��

5

8

0

6

9

+/-

Quality Control 3


QC PassedPress On

12. To obtain the results, press the +/- button. The Control Panel Screen displays:

QAB=xQAS=y

The QC results are reported in terms of QAB and QAS, which are unitlessparameters defined as follows:

QAB is calculated by dividing the measured BUA by the actual phantom BUA valuethat was entered at the factory and also appears on the phantom.

QAS is calculated by dividing the measured SOS by the actual phantom SOS valuethat was entered at the factory and also appears on the phantom.

12. If desired, pressing the +/- button again will display the absolute BUA and SOSvalues. The Control Panel Screen displays:

BUA=xSOS=y

13. A printout of the QC results may be obtained by pressing the PRINT/FEED buttonon the control panel.

3 Quality Control


14. If the QC is outside of normal limits, then the screen will display:

Repeat QC in 1 hourContinue Press ON

In most cases, the cause of the REPEAT message is not a system malfunction but isdue to the phantom not being stabilized at room temperature. Repeat the test in onehour. If you suspect this is the problem, it is acceptable to perform patientmeasurements before completing the QC procedures, as patient results are notaffected by incorrect phantom temperature. However, if this is not believed to be theproblem, or if the repeat message appears after waiting one hour, refer to the QualityControl Problem section of the Chapter 6 - System Care and Maintenance, beforeperforming patient measurements.

15. If the QC results are well outside normal operating limits, and outside of the rangeencountered when the temperature of the phantom is not stabilized, the screen willdisplay:

QC FailedRefer to Manual

Repeat the QC procedure starting at Step 1. If the QC fails again, refer to the QualityControl Problem section of the System Care and Maintenance chapter of thismanual. If the QC Failed message is displayed, do not perform patient examinations

Figure 3-12Press PRINT

Program

Enter

On Open/Prep

MeasurePrint/Feed

1 2 3

4

7

��

5

8

0

6

9

+/-

Quality Control 3


until the QC procedure has been successfully completed or the system has beenserviced.

Recording/Plotting QC ResultsA “PASSED” QC result indicates that the Sahara system is functioning properly. Ifdesired, QAB and QAS results may be recorded and plotted on the Sahara QC worksheetssupplied with the unit. These worksheets allow the daily QC results to be documented andthe long-term stability of BUA and SOS QC results to be visually monitored. Log thedisplayed results on the Quality Control Log sheets provided. Each log sheet canaccommodate one month of QC results, and in order to simplify the graphical plots, onlythe QAB and QAS values are recorded. Note that it is simple to convert the QAB andQAS values to BUA and SOS values by multiplying the QAB value by the phantom BUAvalue (on the phantom label) and by multiplying the QAS value by the phantom SOSvalue (on the phantom label).

At the beginning of each month, a new QC Log sheet should be started by filling in theMonth, Year, Institution Name, System Serial Number, Phantom Serial Number, Phantom

Figure 3-13QC Log

3 Quality Control


BUA, Phantom SOS, and operator name. Note that Phantom Serial Number, BUA andSOS values are given on the label attached to the phantom.

Each day, after the QC measurement is performed, enter the QAB and QAS values on thelog sheet in the "QAB (Rel Units)" and "QAS (Rel Units)" columns, respectively. Makesure that the results are entered into the row labeled with the corresponding day of themonth (i.e. the results obtained on the seventh day of the month are entered in the rowwith a 7 at the left side).

The results can then be plotted on the graph, on the right side of the log sheet. The day ofthe month is indicated along the horizontal axis on each graph, with shading of alternatedays to assist in plotting. The measurement value is indicated on the vertical axis of eachgraph, with breaks in the shaded areas to assist in plotting. Finally, the area between thetwo horizontal dashed lines indicates the normal acceptable range for measurementresults. Note that the PASSED indication on the Sahara control panel screen indicates thatthe results will be in the acceptable range on the plot. QC results may occasionally falloutside of the normal range. In most cases, QC measurements that fall outside of theacceptable range are caused by a phantom that is not stabilized at room temperature,leading to a REPEAT message rather than a PASSED message. If the phantom hasdefinitely stabilized at room temperature for more than one hour, and the system returns aREPEAT message, then it is recommended that the results be recorded in the log andplotted to document the QC failure. See the System Care and Maintenance chapter in thismanual for further information if a PASSED QC result is not obtained.

Interpretation of QC ResultsA “QC PASSED” result indicates that the Sahara system is functioning properly. Thusthe system may be used for patient examinations, regardless of the QAB and QAS values,as long as the “QC PASSED” message is displayed at the conclusion of the QCprocedure. It is common to observe fluctuations in QC results within the normalacceptable range defined by the dashed lines on the Quality Control Log forms.Occasionally, QC results will be outside of these ranges, and repeating the QC procedureafter 1 hour will give acceptable results due to the stabilization of the phantomtemperature. In addition, Sahara also automatically identifies QC results that are farenough outside of the acceptable range as to indicate either a procedural error (no gelused, for example) or a system malfunction. In such a case, the system displays a “QCFailed” message (refer to procedure above for details) and the system should not be usedto evaluate patients until an acceptable result is obtained or the unit is serviced.

Because the variation of the ultrasonic properties of the phantom due to temperature arelarger than the Sahara unit’s short and long term precision, QC results provide aconservative estimate of the performance of the Sahara system. This means that somefluctuation in phantom results would be expected even if the Sahara system had novariation. For this reason, QC phantom results should not be confused with expectedresults in vivo. However, it is important to perform QC in order to verify that the systemis performing properly and that the results are in the acceptable range.

Quality Control 3


Over long periods of time (several months or more), it is typical for the results of the twoQC parameters to have mean (or average) values ranging between 0.93 and 1.07 forQAB and between 0.993 and 1.007 for QAS. That is, the mean values for QAB and QASfall approximately within the middle portion of the acceptable range for each parameter.Note that QC results for a given day, or for a few days, can fall outside of the middle ofthe acceptable range. However, if the QC results are consistently (for more than twoweeks) falling near to the edge of the acceptable limits, the System should be re-calibrated, as described in the System Care and Maintenance Chapter of the User’s Guide.It is important to understand that as long as the QC results fall within the acceptable range(as indicated by the “QC Passed” message) it is acceptable to perform patientexaminations as the system is performing within specifications.

The typical daily fluctuations observed over long periods of time (several months ormore) can be described in terms of the standard deviation (SD) of the QAB or QASresults. Note that in order to obtain a reliable estimate of the SD, at least 2 weeks (10 ormore QC measurements) must be obtained. Typical SD values obtained with Sahara are0.05 for QAB and 0.005 for QAS. If results on your system are poorer than these values,review the QC procedure (above) to insure that the measurements are being performedproperly before contacting your service representative.

3 Quality Control


Patient Measurement 4

Clinical User's Guide 4-1

4 Patient Measurement

This chapter describes how to perform a patient measurement on the Sahara Clinical BoneSonometer.

Warning: If the patient’s skin, in the area to be tested and/or the area that comes intocontact with the Sahara system, transducer pads, or foot positioning aid (i.e. heel, foot, ankle,shin, or calf), is abraded and/or has an open sore, do not measure that heel. If skin isabraded and/or has an open sore on both heels/legs, the patient should not be assessed withthe Sahara system.

Note about Ultrasound Coupling GelsThe selection and proper application of coupling gel are critical in obtaining correctultrasound test results.

Water based gels - used so effectively for qualitative imaging ultrasound modalities -cause a significant delay in pad-to-skin coupling, which can have a significant effect onquantitative ultrasound results. Because Sahara ultrasound measurements are obtained soquickly, the time dependence of quantitative ultrasound results (Figure 4-1) obtainedusing water-based coupling gels will result in unacceptably variable results. Of course thevariability shown in Figure 4-1, while typical of the general population, may vary on anindividual basis. Certain oil based gels also exhibit this time dependence, and it istherefore critical that ONLY Hologic approved ultrasound coupling gels be used withSahara.

Two tubes of Sahara Ultrasound Coupling Gel are supplied with each Sahara unit.Additional tubes can be reordered from Hologic. Use the reorder form included in theSahara starter kit or contact your Hologic representative.

4



In order to obtain highly reproducible results, avoid these common causesof measurement imprecision:

Poor Patient Seating - The patient should be seated in a straight chair without rollers.

Poor Foot Preparation - The foot should be dry and clean when making a measurement.

Improper Foot Placement - Use the exam paper for each measurement as it allows the footto slide easily against the rear of the footwell. Make sure the positioning line is betweenthe second and third toe.

Misuse or Lack of Use of Foot Positioner - Always use the foot positioner. Make sure thatwhen it is applied, the patient is comfortable.

Figure 4-1Comparison of

Ultrasonic CouplingGels



Sahara Patient Measurement Procedure

Prepare Transducer Pads1. Press the ON button. The system initializes itself, closes the transducer pads until

they touch, pauses momentarily, and then opens them for gel application.

Figure 4-2Press ON

Program

Enter

On Open/Prep

MeasurePrint/Feed

1 2 3

4

7

��

5

8

0

6

9

+/-




Note: If there is no operator action within ten minutes after ON is pressed,the unit goes to Power Saver Mode (the screen goes blank). Press theON key to return to the last screen.


Gel PadsPress OPEN

2. For each transducer pad, squeeze out about a one inch (2.5 cm) bead of gel onto yourfinger.



for Gel



Figure 4-5Gel Measurement

Figure 4-6Apply Gel



3. Apply gel evenly on the face of the pad.



Insert FootPress MEASURE

4. When gel has been applied to both transducer pads press the OPEN/PREP button.The scanner opens the transducer pads to the fully open position.

Figure 4-7Gel Application



Position Patient1. The patient should be seated in a stationary, straight-back chair approximately 12 to

18 inches (30 to 46 cm) from the scanner.


Program

Enter

On Open/Prep

MeasurePrint/Feed

1 2 3

4

7

��

5

8

0

6

9

+/-

Figure 4-9Patient Position



2. Ask the patient to remove their shoes, socks, nylons, etc. so that the foot is bare. Ifthe patient’s skin, in the area to be tested, is abraded and/or has an open sore, do notmeasure that heel.

3. Clean the sides of the heel to be measured using towelettes supplied in theAccessories Kit, then dry thoroughly with dry wipes.

4. Place exam paper on the bottom of the scanner foot well.

5. Place the patient’s foot into the foot well. Ensure that the middle of the heel is snugagainst the center of the positioning contour (heel cup) and that the foot is positionedin the well (see the figures below) with the positioning line aligned with the gapbetween the patient’s second and third toe.

Figure 4-10Patient Leg Position



6. Position the patient’s leg at about the same angle as the positioning aid.

Figure 4-11Patient Foot Position

Figure 4-12Heel Position



7. Place the positioning aid down on the leg leaving it slightly loose (about enoughroom to place two fingers between the leg and the positioning aid).

8. Adjust the leg to the angle of the positioning aid by moving the Sahara (the scannerand calf should line up). The figures below show correct, and incorrect, leg angle.

Figure 4-13Positioning Aid Slightly

Loose

Figure 4-14Correct Leg Angle

(front to back)



9. Ensure that the patient’s leg is straight (see the figures below), and push thepositioning aid down firmly to insure it is snug.

Figure 4-15Incorrect Leg Angle

(system too close)

Figure 4-16Incorrect Leg Angle

(system too far)



Figure 4-17Correct Leg Position

(side to side)

Figure 4-18Incorrect Leg Position

(side to side)



10. With the positioning aid down tight, attach the positioning aid strap firmly around theleg.

11. Ensure that the patient is sitting straight up, with their back against the back of thechair and hands folded in their lap. The patient should be comfortable and mustremain still during the measurement.

Figure 4-19Incorrect Position of

Toes

Figure 4-20Positioning Aid Strap



Safety Note: The positioning aid incorporates a safety release mechanism. In the eventthat it is necessary for the patient to remove their foot from the scannerunit at any time during the scan, arching the foot (by pressing the toesdown and lifting the heel up) will release the positioning aid. Detach thepositioning aid strap to remove positioning aid from the leg.

Measure Patient1. Before taking the measurement, double check the patient’s heel to ensure that it is in

the center of the heel cup. If the patient’s heel is not centered, remove the positioningaid and start over at Step 9.

2. Press the MEASURE button on the Control Panel. The system closes the transducerpads to the measurement position and performs the SOS and BUA measurements.The measurement takes less than ten seconds.

3. Upon completion of the measurement the system sounds an audio tone (beep) andopens the transducer pads to the fully open position. The Control Panel Screendisplays:

1) Remove Foot2) Press PREP 3) Clean

4. Remove the positioning aid strap and positioning aid. The positioning aid is releasedby pressing the release latches and lifting the guide (see the figure below).


Program

Enter

On Open/Prep

MeasurePrint/Feed

1 2 3

4

7

��

5

8

0

6

9

+/-



5. Remove the patient’s foot from the scanner unit. Provide the patient with tissues ortowelettes to remove gel from their foot, assist if necessary.

6. Press OPEN/PREP. The scanner moves the transducer pads to the cleaning position.

7. Carefully clean and dry the transducer pads. Use the towelettes supplied in theAccessories Kit to clean the transducer pads, and dry wipes to dry them.

Figure 4-22Removing

Positioning Aid


Program

Enter

On Open/Prep

MeasurePrint/Feed

1 2 3

4

7

��

5

8

0

6

9

+/-



8. The Control Panel Screen displays the Estimated BMD result and corresponding T-score:

Est.Heel BMD=0.340T-Score=-2.2

If the Control Panel Screen displays “Invalid Measurement, Repeat” or “Out-of-Range,Repeat” message, refer to the System Care and Maintenance chapter in this manual.

Note: An asterisk appearing after the Estimated BMD value, indicates thatthe Estimated BMD was calculated using the SOS data alone. TheEstimated BMD is calculated from the SOS alone in those rare caseswhere the BUA data is considered unreliable due to the fact that theassumption of a linear attenuation vs. frequency relationship was notfulfilled. This condition is rare, occurring almost entirely in a smallpercentage of younger males and females with high bone density. Onoccasion, this condition may also be caused by improper footpositioning or not enough coupling gel. Therefore, if the measurementhas an asterisk, it is recommended that the operator repeat themeasurement. If the second measurement does not have an asterisk, itshould be used and the first measurement ignored. If the secondmeasurement also has an asterisk, these results should be interpretedwith caution, especially if used for patient monitoring.

9. Press the Print/Feed button on the Control Panel to obtain a hard copy record ifdesired. Fill in the patient information immediately, before the patient leaves, inorder to avoid confusion later. A sample printout is shown (see “Internal (Strip)Printer Report” and Fig. 4-25 below).

Figure 4-24Cleaning the Pads



If desired, press the +/- button to display the results for the ultrasound parameters(QUI, BUA, and SOS) before conversion to Estimated Heel BMD units (pressing the+/- button again toggles back to the Estimated BMD result). Note that the printedreport will include the QUI, BUA, and SOS results as well as the Est. BMD results ifthe Print/Feed button is pressed when the ultrasound parameters are displayed on theLCD screen.

10. To see the most recent measurement results after the LCD screen has gone blank,press ON to initialize the system, and then press the +/- button to display the resultsof the last examination.

Internal (Strip) Printer ReportSahara Clinical systems may obtain a printed report that includes the measurementresults by pressing the PRINT/FEED button on the Sahara control panel. Note thatthe printed report will include the QUI, BUA, and SOS results as well as the Est.BMD results if the PRINT/FEED button is pressed when the ultrasound parametersare displayed on the LCD screen.

Patient biography data (name, sex, age, etc.) should be noted on the printed reportimmediately after the exam. Remember to indicate the foot measured (Left or Right). Theprinted report will have date and time of the exam.


Program

Enter

On Open/Prep

MeasurePrint/Feed

1 2 3

4

7

��

5

8

0

6

9

+/-



Patient Report FormRefer to Chapter 5 Comparison of Patient Results to Reference Values for information onuse of the Patient Report Form.

Precision of Sahara ResultsThe precision, or reproducibility, of Sahara results was determined by repeated patientmeasurements, with complete re-positioning between measurements. Precision results aregiven in the table below, in absolute units (SD) and in terms of the coefficient of variation(C.V.), which is expressed in percent of the mean value for the population studied.

Parameter SD C.V.

Est. Heel BMD 0.014 g/cm2 3.0%

QUI/Stiffness 2.22 2.6%

BUA 2.64 dB/MHz 3.7%

SOS 3.38 m/sec 0.22%



Considerations for Patient MonitoringGeneral Considerations:

For any type of bone densitometry equipment, the frequency of use for monitoring ofindividual patients is dependent on a number of factors. These factors include theprecision of the device and the expected rate of BMD loss or gain, which is in turndependent on the status of the individual patient. For example, the changes expected dueto aging or disease progression are quite different than those that could be expected forpatients undergoing therapeutic intervention. Furthermore, the expected changes in BMDfor subjects on therapeutic regimens is highly dependent on the type of treatment used(e.g., hormonal replacement therapy, calcitonin, bisphosphonates, etc.). Subjects oncertain treatments for other conditions (e.g. corticosteroids, which are known to rapidlydegrade BMD) are also subject to special consideration. Results of an initial baselineevaluation of BMD are also important, as a patient with high BMD may not need to beevaluated as frequently as a patient with low BMD. Therefore, decisions regardingfollow-up time using Sahara must be individualized, taking into account the patient’s age,disease status, treatment status, baseline BMD results, and other risk factors. Thephysician, who is aware of all of these factors, is thus the most appropriate judge of howfrequently a patient should be evaluated with bone densitometry equipment.

Considerations for Monitoring with Sahara:

For Sahara, the absolute precision error for Est. BMD results is 0.014 g/cm,2 whichcorresponds to about 2.4 times the annual rate of loss in the U.S. Caucasian femalereference population (0.0057 g/cm2/yr). For comparison, standard Dual Energy X-rayAbsorptiometry (DXA) measurements of the spine or hip have a precision error equal toabout 1 to 2 times the annual rate of loss in a reference population. Bone loss rates maybe higher for individual patients immediately after menopause.

From the absolute precision error, the magnitude of the minimum change which can bedetermined with 95% confidence can be calculated:

min. significant change (95% conf.) = 1.96 x 1.414 x 0.014 g/cm2 = 0.0388 g/cm2

This minimum significant change corresponds to about 7% of the mean BMD value for a55 year old caucasian female. This amount of change is approximately what might beexpected after 2 to 3 years of therapy with commonly available treatments. Some patientswill have larger BMD increases, and some will have smaller increases, and thereforefollow-up time will depend on the patient’s individual clinical situation. Changes of thisorder of magnitude may also be expected in as little as 6 months to a year for patientstreated for a variety of conditions such as hyper-parathyroidism and hyper-thyroidism,and may also be observed for patients treated with corticosteroids.



Comparison of Patient Results to a Reference Database 5


5 Comparison of Patient Results to ReferenceValues

This chapter describes standard terminology used for comparison of patient results toreference ranges and the reference ranges supplied with the Sahara Clinical BoneSonometer. The Sahara system provides age dependent reference values for CaucasianU.S. females. These reference values were obtained in a large multi-center study, inwhich Sahara results were obtained for 2208 Caucasian females at 9 clinical centerslocated across the U.S. For situations in which the Caucasian female reference values arenot appropriate, Sahara also provides the capability of entering user defined young adultreference values, enabling automatic comparisons of patient results to these values ifavailable. Guidelines for development, entry, and use of reference values for specificpopulations are described. It is also possible to disable the reporting of referencecomparisons with the Sahara software, for those cases in which no appropriate referencedata exists.

Types of Reference Database ComparisonsIn general, two kinds of comparisons to a reference database can be performed:

1. T-score comparison: T-score is defined as the difference in patient results from themean results obtained in a young adult population, expressed in units of the youngadult population standard deviation. Mathematically, the T-score is defined as:

T = (P-YA)/SDYA

where P = patient results

YA = young adult average value

SDYA = standard deviation of the young adult population

5

5 Comparison of Patient Results to a Reference Database


2. Z-score comparison: Z-score is defined as the difference in patient results from themean results obtained in an age-matched population, expressed in units of the agematched population standard deviation. Mathematically, the Z-score is defined as:

Z = (P-AM)/SDAM

where P = patient results

AM = age-matched average value

SDAM = standard deviation of the age matched population

Reference Database Comparisons Available with SaharaT-score results are automatically calculated (unless disabled by the user) and reportedwith patient Estimated BMD on the LCD display. T-score results similarly included onthe printout obtained by pressing the Print/Feed button.

Z-score results may estimated using the Patient Report Forms, as described below, or maybe calculated manually by the operator using the equation above and the age dependentreference data. When using the Patient Report Forms, estimated Z-scores are based on aCaucasian female population.

Reports

Internal (Strip) Printer ReportPrint each patient measurement immediately after it is taken (see the PatientMeasurement chapter of this manual). The printed report shows the Estimated BMDand he T-score corresponding to the young adult mean and population standarddeviation values. The operator adds the patient biography, referring physician,operator name, and foot measured (left or right) information to the printed report.

The printed report is obtained by pressing the PRINT/FEED button on the Saharacontrol panel. Note that the printed report will include the QUI, BUA, and SOSresults as well as the Est. BMD results if the PRINT/FEED button is pressed whenthe ultrasound parameters are displayed on the LCD screen.



Patient biography data (name, sex, age, etc.) should be noted on the printed reportimmediately after the exam. Remember to indicate the foot measured (Left or Right). Theprinted report will have date and time of the exam.


Program

Enter

On Open/Prep

MeasurePrint/Feed

1 2 3

4

7

��

5

8

0

6

9

+/-



Patient Report FormA tablet of Patient Report Forms is included with each Sahara system. This form isprovided to record patient information and measurement results, and to allow patientresults to be graphically plotted against age dependent US Caucasian female referencevalues.

1. Fill in the biographical information for the patient in the spaces provided.

2. Enter the results of the measurement (Est. BMD and T-score) as reported on the LCDscreen.

3. Staple the printout from the internal strip printer to the Report Form where indicatedto provide a permanent record of results and to insure that no transcription errorswere made.

4. Plot the patient result on the graph of the age dependent reference values andestimate the corresponding Z-score for the patient as described below.

5. Record the estimated Z-score on the form.

Estimating the Z-score and Plotting Patient Results vs. AgeDependent Reference Values:

Z-scores can be manually computed, using the age-dependent reference ranges given inthis section of the User’s Guide, and can be estimated from the Patient Report Form asfollows:

• Mark the plot at the point corresponding to the age and Est. BMD value for thepatient

• The curves shown on the plot correspond to the mean BMD vs. age (middle curve),and 1 and 2 population standard deviations above the mean and below the mean(curves above and below the middle curve).

• If a patient’s result falls exactly on the middle curve, the Z-score is 0.0, and thepatient’s Est. BMD is equal to the mean value for Caucasian female subjects of thesame age.

• If the patient’s result falls exactly on the upper-most curve, the Z-score is +2.0,because it is 2 standard deviations above the age matched mean (middle curve).

• Similarly, if the patient’s result falls midway between the lower-most and next tolower-most curve, the Z-score is -1.5, because it is 1.5 standard deviations belowthe age matched mean (middle curve).



By this method, the patient’s Z-score can be estimated graphically, allowing their resultsto be interpreted both in comparison to age-matched peers (Z-score) as well as to YoungAdult subjects (T-score).

Figure 5-2Patient Report Form



Sahara Caucasian Female Reference Database

Study OverviewThe Sahara Reference Data and Normative Ranges Study was designed to the acquiredata from which age dependent reference values for Caucasian American females couldbe derived. These reference ranges are based on Sahara results for 2208 Caucasianfemale subjects from ages 19 to 97, who were recruited at 9 clinical sites, located acrossthe United States. The large number of clinical sites and subjects enrolled allows formaximum confidence in the reference ranges obtained and also reduces the possibility ofregional bias. This reference data study is unique in that the number of subjects andclinical sites are significantly larger that that of typical manufacturer sponsored referencedata studies for bone densitometry equipment.

Sahara results were obtained for each subject enrolled in the study, as was informationregarding medical conditions and therapeutic regimens that may have an effect on bonemineral metabolism. This information allowed the effects of including or excluding thesesubjects to be evaluated statistically. The study was unique in that even after excludingall subjects with these conditions or treatments, the number of subjects is still larger thanthat of most typical bone densitometry reference data sets.

Clinical Sites for the Sahara Reference Data Study

State City Site Name #Subjects

1 DE Wilmington Alfred duPont Institute 2912 MA Worcester U. Mass. Medical Ctr. 4733 MO St. Louis Washington Univ. 264 NY Manhasset North Shore Univ. Hosp. 2545 PA Philadelphia Presbyterian Medical Ctr. 786 TN Memphis Univ. of Tennessee 2117 UT Salt Lake City Univ. of Utah 988 VT Burlington Univ. of Vermont 3839 WA Seattle Pacific Medical Ctr. 394



Reference Data Ranges for the Sahara Clinical Bone SonometerThe Sahara study data was analyzed by computing the mean values, standard deviations,and percentiles on a decade by decade basis. Statistical testing demonstrated that thepopulation standard deviation was age independent, and that the percentiles described anormal distribution within statistical limits. Statistical testing indicated that the effect ofexcluding subjects with conditions/medications which may effect bone metabolism wasnegligibly small. Thus the final reference ranges were based on all 2208 enrolledsubjects, and consist of the decade specific mean values and the mean (from all thesubjects pooled) population Standard Deviation.

The resultant reference ranges implemented into the Sahara system are tabulated, wherethe mean and population standard deviation are given for each decade. Note that for agesbetween those in the table, reference mean values are obtained by linearly interpolatingbetween the values in the table. The population standard deviation is constant and is notinterpolated. Age dependent reference ranges were similarly analyzed and developed forthe raw ultrasound parameters reported by the Sahara system, including BroadbandUltrasonic Attenuation (BUA), Speed of Sound (SOS), and Quantitative Ultrasound Index(QUI/Stiffness). These reference values are also tabulated below.

Sahara Estimated Heel BMD Reference Data vs. Age

Age(yrs)

Est. Heel BMD(g/cm2)

Standard Deviation(g/cm2)

25 0.581 0.11235 0.555 0.11245 0.562 0.11255 0.545 0.11265 0.471 0.11275 0.436 0.11285 0.373 0.11295 0.339 0.112



Sahara Reference Data vs. Age

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

20 30 40 50 60 70 80 90 100

Age (years)

Est

. Hee

l BM

D

mean +/- 1 pop. SD

Reference Data vs. Age for Sahara Ultrasound Parameters

Mean Value (population SD)Age(yrs)

QUI/Stiffness BUA(dB/MHz)

SOS(m/sec)

25 103.92 (17.65) 76.71 (14.80) 1569.4 (30.43)35 99.88 (17.65) 74.82 (14.80) 1561.4 (30.43)45 100.88 (17.65) 75.89 (14.80) 1562.7 (30.43)55 98.19 (17.65) 74.13 (14.80) 1558.1 (30.43)65 86.53 (17.65) 65.02 (14.80) 1538.7 (30.43)75 80.98 (17.65) 59.81 (14.80) 1530.4 (30.43)85 71.06 (17.65) 51.53 (14.80) 1514.5 (30.43)95 65.65 (17.65) 49.82 (14.80) 1503.0 (30.43)



Modify Young Adult Estimated BMD Reference Values(optional)

Young adult reference values for Estimated Heel BMD are supplied automatically witheach Sahara system. These young adult reference values are specific to United StatesCaucasian female subjects, and are used by the Sahara system to compute T-score resultsfor each patient measurement. T-score results are reported on the LCD screen and on thepaper strip report along with the Estimated Heel BMD.

If a Caucasian female population is not appropriate for the subjects to be assessed, it ispossible to enter locally derived young adult reference values into the Sahara system.Once entered into the system, these local, user defined reference values will thenautomatically be used to compute T-score results for subsequent patient measurements. Itis also possible to disable the T-score calculation, if the US Caucasian female populationis not appropriate and local reference values are not available. To disable the T-scorecalculation, enter 0.0 for both the Young Adult Mean Value and the Young AdultPopulation SD in the procedure described below. Once disabled, the T-score will notappear on the LCD screen or on the paper strip printout.

NOTE: If the young adult reference values have been modified from the original (factoryset) Caucasian female values, the “T-score based on US Caucasian female reference data”annotation at the bottom of the paper strip printout will no longer appear. This annotationwill re-appear if the reference values are re-set to the US Caucasian reference values asgiven in the procedure below and in Section 5 of this User’s Guide.

If local young adult reference values are available, and comparison of patient results tothese values is desired, manually enter the young adult reference values into the Saharasystem following the procedure below. (Guidelines for development of reference valuesare described in the next section.)

To set the young adult reference values in your Sahara system, follow the procedurebelow:


Gel PadsPress OPEN

2. Press PROGRAM, 7, ENTER.



3. The Control Panel Screen displays the previously set young adult BMD referencemean. (Note that 0.581 is the US Caucasian female reference value, and 0.112 is theUS Caucasian female population standard deviation.)

YAdlt BMD Mean=0.5811) Change 2) Exit

4. If you do not wish to change the young adult reference mean, press 2.

5. If you want to set a new young adult reference mean, set the correct mean as follows:


YAdlt BMD Mean=0.581New Value= 0

7. Insert the young adult BMD reference mean, then press ENTER. (0.581 is the USCaucasian female reference value, and entering 0.0 disables the T-score calculation.)The Control Panel Screen then displays the previously set young adult populationstandard deviation:

YAdlt BMD SD=0.1121) Change 2) Exit

8. If you do not wish to change the young adult BMD reference standard deviation,press 2.


ENTER

Program

Enter

On Open/Prep

MeasurePrint/Feed

1 2 3

4

7

��

5

8

0

6

9

+/-



9. If you want to set a new young adult BMD reference standard deviation, proceed asfollows:


YAdlt BMD SD=0.112New Value= 0

11. Insert the young adult BMD reference standard deviation, then press ENTER. (0.112is the US Caucasian female population standard deviation, and entering 0.0 disablesthe T-score calculation).

12. Repeat steps 3-10 to modify the young adult reference values for the QUI parameter,if desired. The US Caucasian female reference values for QUI are: mean = 103.9,SD = 17.6. The Control Panel Screen displays the following:

Gel PadsPress OPEN



Development and Use of Reference Data Ranges for SpecificPatient Populations

The instructions given in the previous section describe how to enter user defined youngadult reference ranges for populations other than US Caucasian females. These youngadult reference values are used to calculate T-scores, which are reported on the LCDdisplay and on the strip paper printout obtained by pressing the PRINT/FEED button onthe keypad. Age dependent reference ranges for Caucasian females are also supplied withSahara, as shown on the Patient Report Form, from which Z-scores are estimated. In thissection, guidelines for development of young adult and age dependent reference valuesfor other populations (such as males, or non-Caucasian females) are described.

Reference values for specific populations can either be obtained from published scientificliterature, or alternatively, may be developed by the physician. When using referencevalues obtained from published scientific literature, it is important to verify that thepopulation studied is applicable to the patients that you will be evaluating, and that theguidelines described below have been followed in the published study.

Guidelines for Development and Use of Young Adult ReferenceValues:

A minimum of 50 subjects between the ages of 20 and 30 years should be recruitedrandomly from the target population. A single Sahara measurement should be performedon each subject. If the Sahara result is marked by an asterisk (indicating unreliableultrasound results as described in Chapter 4, Patient Measurement), the patient should berepositioned and the measurement should be repeated. If the second measurement also ismarked by an asterisk, the patient’s results should not be used for the development of thereference values, and an additional subject should be recruited. If the secondmeasurement is not marked by an asterisk, then it is acceptable to include the secondresult in the calculation of young adult reference values. For each subject, press the +/-key on the keypad prior to pressing the PRINT/FEED key, in order to get a hardcopyprintout that includes all of the ultrasound parameters.

Results for the 50 subjects should be analyzed to determine the mean (or average) valueand the population standard deviation (SD) value for each Sahara output parameter (Est.BMD, QUI, BUA, and SOS). The mean value and standard deviation can be computedusing most hand-held scientific calculators, and does not require sophisticated computersoftware.

Check that the SD value for the Est. BMD is in the range of 0.070 to 0.150 g/cm.2 If theSD is not in this range, it is possible that an error was made in the calculation of the SD.Check that the mean value for the Est. BMD is in the range of 0.400 to 0.700 g/cm.2 Ifthe mean value is not in this range, it is possible that an error was made in the calculation



of the mean. Note that any values may be entered into the Sahara system for the meanand SD, and there may be populations for which values outside of these ranges are valid,but most populations should have values that fall in these ranges.

Enter the mean and population SD values into the Sahara system using the proceduredescribed in the preceding section. For the first patient evaluated, perform the T-scorecalculation manually using the equation given earlier in this chapter (see Types ofReference Data Comparisons), in order to check that the mean and population SD wereentered properly.

Guidelines for Development and Use of Age Dependent ReferenceValues:

A minimum of 50 subjects for each decade of age should be recruited randomly from thetarget population. A single Sahara measurement should be performed on each subject. Ifthe Sahara result is marked by an asterisk (indicating unreliable ultrasound results asdescribed in Chapter 4, Patient Measurement), the patient should be repositioned and themeasurement should be repeated. If the second measurement also is marked by anasterisk, the patient’s results should not be used for the development of the referencevalues, and an additional subject should be recruited. If the second measurement is notmarked by an asterisk, then it is acceptable to include the second result in the calculationof young adult reference values. For each subject, press the +/- key on the keypad priorto pressing the PRINT/FEED key, in order to get a hardcopy printout that includes all ofthe ultrasound parameters.

Results for the subjects in each decade of age should be analyzed independently todetermine the mean (or average) value and the population standard deviation (SD) valuefor each Sahara output parameter (Est. BMD, QUI, BUA, and SOS). The mean value andstandard deviation can be computed using most hand-held scientific calculators, and doesnot require sophisticated computer software.

Check that for the 20 - 30 year age group the SD value for the Est. BMD is in the range of0.070 to 0.150 g/cm.2 If the SD is not in this range, it is possible that an error was madein the calculation of the SD. Check that for the 20 - 30 year group the mean value for theEst. BMD is in the range of 0.400 to 0.700 g/cm.2 If the mean value is not in this range, itis possible that an error was made in the calculation of the mean. Note that any valuesmay be entered into the Sahara system for the mean and SD, and there may be populationsfor which values outside of these ranges are valid, but most populations should havevalues that fall in these ranges.

Z-scores may be obtained either graphically, by generating a reference data plot similar tothe one on the Sahara Patient Report Form, or using the equation for Z-score given earlierin this chapter (see Types of Reference Data Comparisons). The results for each of thedecade averages correspond to the results at the middle of the decade, i.e., the results forthe 20 - 30 year decade correspond to the results for age = 25. The decade by decade



results therefore correspond to values for ages 25, 35, 45, etc. For ages in between these,the reference values are obtained by linear interpolation. Thus the reference value for age= 50 is the average of the age 45 and 55 values.

System Care and Maintenance 6


6 System Care and Maintenance

This chapter describes care and maintenance procedures on the Sahara Clinical BoneSonometer. It covers ordering supplies, cleaning the unit, printer maintenance, transducerpad care and maintenance, and what to do if a problem occurs.

Ordering SuppliesTo order Sahara Ultrasound Coupling Gel, towelettes, dry wipes, Examination paper,printer paper, or other supplies for the Sahara system:

International customers should contact their authorized Hologic distributor.

USA customers may complete a reorder card or call Hologic at (800) 321-4659.

Cleaning and Re-UseThe Sahara Clinical Bone Sonometer is a reusable device and is considered a noncriticaldevice for infection control practices. The transducer pads, foot well, control panel,positioning aide and rest of the scanner are the surfaces of the Sahara unit that may becleaned between use.

How SuppliedTowelettes and dry wipes are supplied with the Sahara system for cleaning of gel from thetransducer pads, phantom, and patient. The towelettes supplied are standard baby-wipes,which are a commonly available over the counter product. Additional towelettes may bepurchased either from Hologic, or at any local pharmacy or supermarket. The dry wipessupplied (Kim-wipes®, manufactured by Kimberly-Clark) are a standard product,commonly available from medical supplies dealers and medical supplies catalogs.Additional dry wipes may be ordered from Hologic, or purchased through your medicalsupplies dealer or catalog. It is acceptable to substitute other equivalent brands of dry wipes,

6



if Kim-wipes® are not available, but it is NOT acceptable to use facial tissues, which canleave residues and particles on the transducer pads.

Infection ControlHologic recommends the use of Cavicide® disinfecting cleaner to clean the Sahara unit’ssurfaces between use. Cavicide1 is a disinfecting cleaner that destroys pathogens and othermicroorganisms. Cavicide is available by contacting the Metrex Research Corporation, IL{phone# (800) 841-1428}.

The chemical composition of Cavicide is:

Active Ingredients:

Diisobutylphenoxyethoxyethyl dimethyl benzyl ammonium chloride 0.25%

Isopropanol 15.30%

Inert Ingredients 84.45%-----------

Total 100%

Cavicide has been tested on inanimate surfaces against:

• Staphylococcus aureus

• Pseudomonas aeruginosa

• Salmonella choleraesuis

• Mycobacterium tuberculosis var: bovis (BCG)

• Methicillin Resistant Staphylococcus aureus (MRSA)

• Vancomycin Resistant Enterococcus faecalis (VRE)

• Trichophyton mentagrophytes

• Herpes simplex virus types 1 and 2

• Human Immunodeficiency Virus (HIV-1)

• Poliovirus types 1 and 2

• Coxsackievirus

1 EPA Reg No.: 38526-1. EPA Est. No.: 39234-WV-1



Cleaning FrequencyThe transducer pads and foot well should be cleaned after each patient or phantommeasurement. The rest of the scanner and positioning aide may be cleaned as necessary.

How to Clean/Disinfect the Sahara Unit

CleaningRemove all coupling gel first from transducer pads, after each patient or phantommeasurement by wiping the surface with the towelettes or dry wipes supplied with the Saharaunit. Spray Cavicide disinfectant cleaner on transducer pads, foot well, positioning aide, andother scanner surfaces as necessary. Wipe clean using the towelette or dry wipes. Discard theused towelette or dry wipe.

DisinfectingRemove all coupling gel first from transducer pads, after each patient or phantommeasurement by wiping the surface with the towelettes or dry wipes supplied with the Saharaunit. Spray Cavicide disinfectant cleaner on transducer pads, foot well, positioning aide, andother scanner surfaces as necessary. Allow to remain wet for 3 minutes at room temperature.Follow by wiping clean with the towelette or dry wipe. Discard the used towelette or drywipe.

Additional MeasuresAs an additional precautionary measure, exam paper should be placed under the patient’sfoot on the Sahara unit, during use, to provide a physical barrier against possible soiling orcontamination. Exam paper should be discarded after every single patient measurement.

Alternate PracticesIf another disinfectant cleaner provides the same level of protection as Cavicide, thecustomer, at their own discretion, may clean the Sahara unit’s surfaces with an alternateproduct.

Always clean any gel thoroughly off the exterior of the scanner with a towelette. Paycareful attention to ensure that the foot well and control panel are clean. Also, clean therest of the scanner and positioning aid as necessary.



Care and Maintenance of Transducer Pads

Warning: The Sahara system must be calibrated after removing or replacing transducerpads. Therefore it is important not to remove the transducer pads unlessnecessary. If the transducer pads become damaged and do need to be removed orreplaced, it is imperative that the instructions below be carefully followed toensure proper system performance. Never store the phantom in the unit footwellwith the pads closed on it, as this will destroy both the pads and the phantom.

Care of Transducer PadsTransducer pads should be cleaned, removing all coupling gel, after each patient orphantom measurement as specified in the measurement procedures in this manual. Use thetowelettes supplied with the Sahara system to remove gel from the pads, and then the drywipes (supplied) to dry the pads.

Note: When cleaning the transducer pads, it is acceptable to substitute otherequivalent brands of dry wipes if Kim-wipes® are not available, but it isNOT acceptable to use facial tissues, which can leave residues andparticles on the transducer pads that could degrade systemperformance.

Rubbing alcohol may also be used to remove built-up dirt or stains on the pads, followedby wiping with towelettes and dry wipes. Do not remove the pads from the unit to cleandirt or stains.

Do not touch the transducer pads with any sharp objects, as cuts or tears in the pads willeffect system performance. Replace torn, cut, or damaged pads immediately following theprocedures described below.

Inspect the pads occasionally, looking especially at the surfaces that contact the heel.Replace pads if there is damage (pitting, tears, cuts) to these surfaces.

Transducer Pad DiscolorationThe transducer pads will discolor to a dark red, purple, or black if left in contact with thephantom supplied with the instrument. Customers are alerted to this fact in the ClinicalUser’s Guide in several places. If the phantom and transducer pads are left in contactwith one another for an extended period, discoloration of the pads may occur. Minordiscoloration, particularly on the edges of the pads, has no impact on the performance ofthe machine. In the event of major discoloration of the pad faces, it may be necessary toreplace both the pads and phantom. If QC continues to pass after discoloration occurs,the discoloration is merely cosmetic. If, however, QC failures occur at the same time



major discoloration is noticed, the pads require replacement and the instrument must berecalibrated. Additionally, check the phantom for deformity in the area of pad/phantominterface. If the phantom is noticeably deformed, a new phantom is necessary.

Transducer pads will slowly and evenly turn yellow over the course of several months.This is due to UV (ultraviolet) degradation of the surface of the pads and does not affectthe instrument’s performance.

Removal/Replacement of Transducer PadsNote: Transducer pads must always be replaced in pairs. Do not replace one

pad without replacing the other.

Transducer pads may be removed, cleaned, and re-installed if they are excessively dirty.Follow the procedure for replacing the pads below, re-installing the same pads (aftercleaning with towelettes and dry wipes) rather than installing new pads.

If one or both transducer pads has become damaged (cut, torn, or has become pitted)replace both transducer pads following carefully the procedure below. This procedureincludes system re-calibration, which must be performed any time the pads have beenremoved or replaced.

1. Unscrew the transducer pad housing (see the figure below).

2. Clean the transducer face (see figure below) with towelettes and dry wipes, makingsure not to leave any residual coupling gel on the transducer face.

Figure 6-1Remove Transducer Pad

Housing



3. Locate the bag containing the replacement transducer pads and remove one pad.Clean the new pad with towelettes, and dry with dry wipes to remove any dirt, lint,etc. Visually inspect the pad, looking for tears or cuts in the surface, especially theends of the pad.

4. Place the pad in the housing making sure the key, on the pad, is aligned to the correctslot (see the figures below). Pull on the end contacting the heel to finish seating andaligning the pad.

The figures below shows how to align the left and right transducer pads:

Figure 6-2Cleaning Transducer

Face



5. Apply Hologic Sahara Pad Installation Gel, which is included in the pad replacementkit, to the flat end of the pad before positioning it in place in the system. Spread thegel evenly with your finger so that there is about a 1/16 inch (1.6 mm) coating on thepad. Be careful not to introduce air bubbles, dirt or other contaminants (see the figurebelow).

Figure 6-3Right Transducer Pad

Alignment

Figure 6-4Left Transducer Pad

Alignment



6. With gel applied, screw the housing/pad onto the transducer as far as it will go. Theguide mark on the Sahara enclosure should line up with the mark on the transducerhousing (see the figure below). Repeat steps 1-6 for the other transducer pad.

7. With both pads installed, the system should look like the figure below (note theposition of the leading edge of the transducer pads). If the pads are not correctly

Figure 6-5Pad Gel Application

Figure 6-6Pad Guide Marks



installed, remove them, clean all surfaces including transducer face with a no-linttissue, and repeat the procedure from the beginning.

Calibrate SystemThe Sahara system must be calibrated after removing/replacing transducer pads. Followthe procedure below.

System CalibrationEach Sahara is supplied with a QC phantom which can also be used to calibrate thesystem.

System calibration is not usually necessary unless the transducer pads are removed, or amalfunction has occurred requiring service. To perform system calibration, follow theprocedure below.

Note: It is important that the system and phantom have equilibrated to roomtemperature for at least one hour before performing this procedure.

Figure 6-7Pads Installed Correctly



1. Press the ON button. The system initializes itself and closes the transducer pads untilthey touch, and then opens them for gel application.

Figure 6-8Press ON

Program

Enter

On Open/Prep

MeasurePrint/Feed

� � �

�

�

��

�

�

0

�

+/-




Note: If there is no operator action within ten minutes after ON is pressed,the unit goes to Power Saver Mode (the screen goes blank). Press theON key to return to the last screen.

2. Press the PROGRAM button, then the 2 button and then ENTER on the controlpanel. This initiates calibration of the system.

The Control Panel Screen displays the following message:


for Gel


ENTER

Program

Enter

On Open/Prep

MeasurePrint/Feed

� � �

�

�

��

�

�

0

�

+/-



CAUTION - Enter calibprocedure? 1) Yes 2) No

3. Press 1 to start calibration (if 2 is pressed the system will return to the “Gel Pads -Press OPEN” screen).

Note: The phantom should not be in place at this point.

The Control Panel Screen displays the following message:

Calib takes 15 minContinue? 1) Yes 2) No

4. Press 1 to continue calibration (if 2 is pressed the system will return to the “Gel Pads- Press OPEN” screen). The Control Panel Screen displays the following message:

Phantom LabelBUA= 0_________

5. Enter the BUA number from the phantom label, and press ENTER. The ControlPanel Screen displays the following message:

Phantom LabelSOS= 0_________

6. Enter the SOS number from the phantom label, and press ENTER. The ControlPanel Screen displays the following message:

Phantom LabelWidth= 0_________

7. Enter the width number from the phantom label, and press ENTER. The ControlPanel Screen displays the following message:

Phantom LabelS/N= 0_________

8. Enter the serial number from the phantom label, and press ENTER. The ControlPanel Screen displays the following message:



[1 of 5] Gel pads2) Press OPEN

9. For each transducer pad, squeeze out about a one inch (2.5 cm) bead of gel ontofinger (see the figure below).


10. Apply gel to the transducer pad. Cover the entire surface area of the pad making surethat the leading edge of the pad is covered (see the figure below).


Figure 6-12Measure Gel



11. When gel has been applied to both transducer pads press the OPEN/PREP button.The system opens the transducer pads to the fully open position.

Figure 6-13Apply Gel

Figure 6-14Gel Application



12. Place the QC phantom in the Sahara. Position the phantom so that its rounded end issnugly in the positioning contour (heel cup), and the flat side of the phantom is lyingflat against the bottom of the system (see the figure below).

13. Press the MEASURE button. The system performs a measurement, thenautomatically opens the transducer pads.


Program

Enter

On Open/Prep

MeasurePrint/Feed

� � �

�

�

��

�

�

0

�

+/-

Figure 6-16QC Phantom in Position



14. Remove the phantom.

15. Press OPEN/PREP. The transducer pads return to the ready position.

16. Carefully clean and dry the phantom and the transducer pads. Use the towelettessupplied in the Accessories Kit to clean the phantom and transducer pads, and drywipes to dry them.

Note: It is important that the phantom and the transducer pads arethoroughly cleaned and dried after every pass of the calibrationprocedure.

17. Press ON. The Control Panel Screen displays the following message:


Program

Enter

On Open/Prep

MeasurePrint/Feed

� � �

�

�

��

�

�

0

�

+/-


Program

Enter

On Open/Prep

MeasurePrint/Feed

� � �

�

�

��

�

�

0

�

+/-



[2 of 5] Gel pads2) Press OPEN

18. Repeat Steps 9 through 16 until all 5 passes of the calibration procedure arecomplete. The Control Panel Screen displays the following message at thecompletion of the procedure:

CalibrationSuccessful

19. Press ON. This completes the calibration procedure. The device will print out thecomplete calibration records. Please save them for future reference.

20. Perform a QC measurement following the procedure in the chapter titled QualityControl in this manual.

Calibration FailureIf the calibration procedure fails, the Control Panel Screen displays the followingmessage:

Calibration FailedPlease Repeat

If this occurs, the calibration has not been changed. Start the procedure over from thebeginning. Repeat all steps carefully.

If the calibration procedure fails again, wait at least one hour for the phantom to stabilizeat room temperature and repeat the procedure from the beginning. Repeat all stepscarefully.

If the calibration procedure fails a third time, call your authorized Hologic servicerepresentative.



Printer OperationFollow the procedure below to load printer paper:

1. Remove the printer cover by sliding the cover towards the rear.

2. Grasp the paper roll in your hand and feed the paper through the printer as shown inStep 1 of Figure 6-20 and Figure 6-21. Insert the paper into the paper slot wherearrows indicate. The paper should feed from the underside of the roll.

Figure 6-19Removing Printer Cover

Figure 6-20Threading Printer

Paper



3. To feed the paper press the PRINT/FEED button while the display screen isdisplaying “Gel Pads press OPEN”.

4. Place the paper roll into the printer tray. Insert the paper roll in the tray as shown inFigure 6-22 and Step 2 of Figure 6-20.

5. Insert the paper through the slot in the printer cover and reinstall the cover.

Figure 6-21Feed Printer Paper

Figure 6-22Insert Paper Roll



Note: Never pull the paper (either forwards or backwards) through theprinter. Always advance the paper using the Print/Feed button, andtear off using the cover slit.

Figure 6-23Printer Cover Replaced



Display Serial NumberTo display the unit’s serial number from your Sahara system, follow the procedure below:


Gel PadsPress OPEN

2. Press PROGRAM, 6, ENTER. The Control Panel Screen displays the serialnumber.

Serial Number=XXXXXXX

3. After the serial number displays briefly, the Control Panel Screen displays:

Gel PadsPress OPEN


ENTER

Program

Enter

On Open/Prep

MeasurePrint/Feed

1 2 3

4

7

��

5

8

0

6

9

+/-



What to do in Case of TroubleThis section provides information to assist the user in case something goes wrong with thesystem.

Acquiring Results After a Paper Jam/Clearing a Printer Paper JamIf any of the following printer problems occur:

� the printer paper jams, or

� the edge of the paper frays or tears, or

� the printer does not feed paper continuously,

stop further printing and perform the procedure below to obtain measurement results andclear the printer.

In the event of a printer jam, before unplugging the machine, follow the proceduredescribed below in order to obtain the results.

1. Press ON, to clear the error message from the screen. The screen will display

Initializing…

2. Press the +/- key once. This will display the QUI and T-Score results from themeasurement calculated before the printer jam. Write these results down. Oncethe instrument is unplugged these results will be lost.

3. Press the +/- key again. The BUA and SOS results will be displayed. Writethese results down.

4. Unplug the unit.

5. Remove the printer cover from the machine (refer to Printer Operation in thischapter).

6. Remove as much paper as possible. Tweezers or long nose pliers may benecessary for this step. A straightened paper clip may be used if those tools arenot available.

7. Clip off the end of the paper roll with scissors to obtain a straight edge.

8. Plug the unit back in. Refer to the section Initial Set Up to reload the paper.



Printer Operates but Does Not PrintIf this occurs, the printer paper may be installed backwards. The printer uses thermalpaper that is coated on one side only. To correct this problem, carefully remove the roll ofpaper and reinstall correctly.

Power ProblemIf the screen does not display Version Number when power is applied, check thefollowing:

� Is the power supply plugged into the system?

� Is the power cord plugged into the power supply?

� Is the power cord plugged into the wall outlet?

� Are you certain there is power at the wall outlet? If not, try another outlet.

� Is the power status light (small green light near the system power connector) on? Ifall of the above conditions are OK, and the power status light is off, there may be aproblem with the power supply.

� Try unplugging the system from the wall outlet, waiting a few seconds, and pluggingit in again. This causes the system to automatically run an internal diagnostic testwhich may clear the problem. If this does not clear the problem, contact yourauthorized Hologic service representative.

System Malfunction and Error LogThere are extensive diagnostics embedded in the Sahara system to monitor the operatingperformance of the software, electronics and mechanical aspects of the product. When amalfunction occurs, the type of malfunction is automatically stored in an internal log andone of the following messages is displayed:

Power On Self Test:Failed

followed by:

Error Code=aCat=b HiCat=c

Or:



Fault: Mid=a Pid=bVid=c FC=d e

followed by:

xxxxxxxxxxxxxxyyyyyyyyyyyyyy

If this message is seen:

International customers should contact their authorized Hologic servicerepresentative.

US customers should contact Hologic Customer Service at (800) 321-4659.

The service department will ask you to print out an exception report. Make sure the unit ispowered on and follow the procedure below to print an exception report.

Printing the Exception Report1. Press ON and wait for the pads to move apart.

2. Press PROGRAM.

3. Press 4.

4. Press 2.

5. Press ENTER.

6. Press 9.

7. Press 3.

8. Press ENTER.

The printer will print an exception report (see example below):



FAX this to your authorized Hologic service representative.

Quality Control ProblemAt the completion of the Quality Control procedure (using the QC phantom) the ControlPanel Screen should display the word Passed. If the system fails this procedure theControl Panel Screen will display:

QC FailedRefer to Manual

If, after trying the procedure twice, the system does not pass, check the following:

1. Is the small green light (near the scanner power connector) on? If all of the aboveconditions are OK, and the green power indicator light is off, there may be a problemwith the power supply.

2. Try unplugging the system from the wall outlet and plugging it in again. This causesthe system to automatically run an internal diagnostic test which may indicate or clearthe problem.

3. Is the system (including the phantom) acclimated to room temperature? Temperatureis the most likely cause of this problem. If you are not sure if the system (includingthe phantom) is acclimated to room temperature, wait at least one hour with thesystem on, then try again.

4. If the transducer pads have been removed or replaced, has the procedure beenfollowed carefully (including calibration)? Check the procedure titledRemoval/Replacement of Transducer Pads in this manual, and repeat it if necessary.Ensure that the pad couplant is spread evenly (about a 1/16 inch coating) on the flat



side of the pad. Ensure that the transducer housings are screwed in securely (so thatthe guide marks line up).

5. If the above does not fix the problem:

International customers should contact their authorized Hologic servicerepresentative.

US customers should contact Hologic Customer Service at (800) 321-4659.

Patient Measurement Problems

Asterisk after Estimated BMD result (Est. BMD = 0.500* g/cm2)An asterisk appearing after the Estimated BMD value, indicates that the EstimatedBMD was calculated using the SOS data alone. The Estimated BMD is calculatedfrom the SOS alone in those rare cases where the BUA data is considered unreliabledue to the fact that the assumption of a linear attenuation vs. frequency relationshipwas not fulfilled. This condition is rare, occurring almost entirely in a smallpercentage of younger males and females with high bone density. On occasion, thiscondition may also be caused by improper foot positioning or not enough couplinggel. Therefore, if the measurement has an asterisk, it is recommended that theoperator repeat the measurement. If the second measurement does not have anasterisk, it should be used and the first measurement deleted from the database. If thesecond measurement also has an asterisk, these results should be interpreted withcaution, especially when used for patient monitoring.

Invalid Measurement, RepeatThis error indicates that the unit could not make a proper measurement. Some possiblecauses of this error are:

� foot moved during measurement

� inadequate gel on pad tips

� no foot between the pads

� measured heel width outside of specified foot size range

If the patient’s foot size is outside of the specified foot range (see Specifications inChapter 1 of this User’s Guide), the patient cannot be assessed with Sahara. Otherwise,



repeat the measurement. If, after three attempts to measure a patient the display stillindicates REPEAT, contact your authorized Hologic service representative.

Measurement Out-of-RangeThis error indicates that the calculated SOS and/or BUA is outside the unit’smeasurement range. Some possible causes of this error are:

� inadequate gel on pad tips

� something between pads and foot (stockings on?)

Repeat the measurement. If, after three attempts to measure a patient the display stillindicates REPEAT, contact your authorized Hologic service representative.

